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Topic:Mitochondria

Mitochondria are organelles found in the cells of horses that are responsible for producing energy through the process of oxidative phosphorylation. They play a role in various cellular functions, including energy metabolism, regulation of the cell cycle, and apoptosis. Mitochondria contain their own DNA, which is maternally inherited and can provide insights into genetic lineage and population studies in equines. Research on equine mitochondria encompasses topics such as mitochondrial function, genetic variation, and their implications for health and performance. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and genetic aspects of mitochondria in horses.
Assessment of equine sperm mitochondrial function using JC-1.
Theriogenology    September 1, 2000   Volume 53, Issue 9 1691-1703 doi: 10.1016/s0093-691x(00)00308-3
Gravance CG, Garner DL, Baumber J, Ball BA.The fluorescent carbocyanine dye, JC-1, labels mitochondria with high membrane potential orange and mitochondria with low membrane potential green. Evaluation of mitochondrial membrane potential with JC-1 has been used in a variety of cell types, including bull spermatozoa; however, JC-1 staining has not yet been reported for equine spermatozoa. The aim of this study was to apply JC-1 staining and assessment by flow cytometry or a fluorescence microplate reader for evaluation of mitochondrial function of equine spermatozoa. Six ejaculates from four stallions were collected and centrifuged thro...
Fine structure of the retinal pigment epithelium, Bruch’s membrane and choriocapillaris in the horse.
Anatomia, histologia, embryologia    August 5, 2000   Volume 29, Issue 3 135-139 doi: 10.1046/j.1439-0264.2000.00241.x
Altunay H.The fine structure of the retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris was investigated by light and transmission electron microscopy in both the tapetal and non-tapetal fundus of the horse eye. In all locations, the RPE consisted of a single layer of low cuboidal cells. The epithelial cells were joined laterally by apically located tight junctions. These cells displayed numerous basal infoldings and abundant thin apical processes which enclosed the rod outer segments. The epithelial cell nuclei were large and located basally. Within the epithelial cells, smooth endo...
Establishment and characterization of equine autonomic ganglion cell lines to enable direct testing of candidate toxins involved in equine dysautonomia (grass sickness).
Cell biology and toxicology    July 13, 2000   Volume 16, Issue 1 63-74 doi: 10.1023/a:1007648721564
John HA, Laffling AJ, Marrs J, Baird A, Jat PS, Holdstock NB, Rossdale PD.To enable direct testing of a range of potential toxins or pathogens that might be involved in grass sickness, equine thoracic sympathetic chain ganglion cell lines were established from primary cell cultures by retroviral-mediated transduction of the temperature-sensitive mutant of the establishment oncogene encoding SV40 large T antigen. Morphological and behavioral features, temperature dependence, and immunocytochemical characteristics of the cell lines were investigated. The majority of cells were noradrenergic neurons in which dopamine-beta-hydroxylase, the enzyme that catalyzes norepine...
Detection of steroidogenic acute regulatory protein in equine ovaries.
Journal of reproduction and fertility    June 24, 2000   Volume 119, Issue 2 187-192 
Watson ED, Thomson SR, Howie AF.A steroidogenic acute regulatory (StAR) protein has been identified in several species as a probable important rate-limiting step in steroidogenesis. This protein is believed to be responsible for transporting cholesterol from the outer to the inner mitochondrial membrane. It is known that equine chorionic gonadotrophin (eCG) stimulates steroidogenesis in the corpora lutea of early pregnant mares and that eCG also upregulates StAR mRNA in bovine ovaries. In the present study, ovarian tissue from cyclic and early pregnant mares was immunostained to detect the distribution of the StAR protein. W...
A pedigree-based study of mitochondrial D-loop DNA sequence variation among Arabian horses.
Animal genetics    February 26, 2000   Volume 31, Issue 1 1-7 doi: 10.1046/j.1365-2052.2000.00558.x
Bowling AT, Del Valle A, Bowling M.Through DNA sequence comparisons of a mitochondrial D-loop hypervariable region, we investigated matrilineal diversity for Arabian horses in the United States. Sixty-two horses were tested. From published pedigrees they traced in the maternal line to 34 mares acquired primarily in the mid to late 19th century from nomadic Bedouin tribes. Compared with the reference sequence (GenBank X79547), these samples showed 27 haplotypes with altogether 31 base substitution sites within 397 bp of sequence. Based on examination of pedigrees from a random sampling of 200 horses in current studbooks of the A...
Muscular and metabolic responses to moderate-intensity short-term training.
Equine veterinary journal. Supplement    February 5, 2000   Issue 30 311-317 doi: 10.1111/j.2042-3306.1999.tb05240.x
Geor RJ, McCutcheon LJ, Shen H.The objectives of this study were to determine the effects of 10 consecutive days of moderate-intensity training on 1) the muscular metabolic response to exercise at 100% of the pre-training maximum rate of oxygen consumption (VO2max); and 2) mitochondrial enzyme markers (citrate synthase, CS; succinate dehydrogenase, SDH; 3-hydroxy-acyl-CoA dehydrogenase, HAD) of oxidative capacity in middle gluteal muscle. Six mature, unfit Thoroughbred horses completed both incremental (for determination of VO2max) and high-intensity exercise protocols before (HI1) and after (HI2) training. Training consist...
[Functional morphology of the large intestinal mucosa of horses (Equus przewalskii f. caballus) with special regard to the epithelium].
Anatomia, histologia, embryologia    February 1, 2000   Volume 28, Issue 5-6 355-365 doi: 10.1046/j.1439-0264.1999.00223.x
Wille KH, Nakov C.The mucous membrane of the caecum and colon ascendens of adult horses was first studied using light and transmission electron microscopy. In the surface epithelium there was an inconspicuous constellation of organelles, otherwise there was a lot of mitochondria as a source of energy for absorptive performances. Moreover, enlarged intercellular spaces exist as an indication of an increased uptake of water and electrolytes. In the basal region of Lieberkühn's crypts there were single enteroendocrine cells and numerous granules in the apical epithelial cytoplasm. The functional meaning of these ...
Equine sarcoid tumour treated by autogenous tumour vaccine.
Anticancer research    January 12, 2000   Volume 19, Issue 4C 3367-3374 
Kinnunen RE, Tallberg T, Stenbäck H, Sarna S.Twenty-one horses with sarcoid tumours were treated by bio-immunotherapy using autogenous vaccines during 1991-1997. At operation the base of the tumour was left in the skin and autovaccines were made from extirpated tumour tissue by polymerization. The horses thus formed their own internal control group. One of 12 horses having a primary tumour, and four of 9 horses suffering recurrent tumours, prior to bio-immunotherapy, developed single recurrences. Four of these five horses suffering recurrence were treated anew, leading to remission. Disease-free intervals were longer for primary (P = 0.0...
Ultrastructure, protein phosphorylation and mRNA status of equine oocytes matured in vivo and in vitro.
Journal of reproduction and fertility. Supplement    January 1, 2000   Issue 56 473-482 
Alm H, Neumann H, Torner H, Tomek W, Wollenhaupt K, Kanitz W, Becker F.Equine oocytes were collected by follicle aspiration in vivo or by dissection of material obtained from an abattoir, and the ultrastructure, protein phosphorylation and mRNA status of the oocytes were evaluated. Electron microscopy studies indicated that the nucleus had a smooth membrane in oocytes with a compact cumulus, whereas the nuclear membrane was undulated in all other groups. Oocytes with compact cumuli had only a few microvilli, whereas those with expanded cumuli had more microvilli. There were only small numbers of cortical granules close to the oolemma in oocytes with compact cumul...
Mitochondrial D-loop sequence variation among the 16 maternal lines of the Lipizzan horse breed.
Animal genetics    December 28, 1999   Volume 30, Issue 6 423-430 doi: 10.1046/j.1365-2052.1999.00557.x
Kavar T, Habe F, Brem G, Dovc P.Mitochondrial DNA from 49 Lipizzan horses representing 16 maternal lines from the original stud at Lipica was used for SSCP analysis and DNA sequencing. The SSCP analysis of the 444 bp long fragment of the D-loop region extending from the tRNA(Pro) gene to the central conserved sequence block revealed three distinct groups of SSCP patterns. Both ends of the D-loop region (378 bp and 310 bp), which are considered as the most variable regions within the mammalian mitochondrial DNA, were sequenced. According to 49 polymorphic sites identified within the both parts of the D-loop region, the 16 mat...
Phylogenetic relationships of Cheju horses to other horse breeds as determined by mtDNA D-loop sequence polymorphism.
Animal genetics    June 22, 1999   Volume 30, Issue 2 102-108 doi: 10.1046/j.1365-2052.1999.00419.x
Kim KI, Yang YH, Lee SS, Park C, Ma R, Bouzat JL, Lewin HA.Historical records suggest that horses inhabiting the island of Cheju in Korea are descendants of Mongolian horses introduced in 1276. Other studies, however, suggest that horses may have been present on the island prior to the Mongolian introduction. To determine the origin of the Cheju horses we used a phylogenetic analysis of sequences of the mitochondrial DNA (mtDNA) D-loop region, including tRNA Pro and parts of tRNA thr and tRNA Phe sequences (1102-bp excluding the tandem repeat region). Maximum parsimony and neighbor-joining trees were constructed using sequences determined for seven Ch...
Streptococcus equi but not Streptococcus zooepidemicus produces potent mitogenic responses from equine peripheral blood mononuclear cells.
Veterinary immunology and immunopathology    April 9, 1999   Volume 67, Issue 3 235-246 doi: 10.1016/s0165-2427(98)00227-x
Anzai T, Sheoran AS, Kuwamoto Y, Kondo T, Wada R, Inoue T, Timoney JF.Streptococcus equi causes equine strangles. The acute disease has many of the hallmarks of an acute response including high fever, elevated plasma fibrinogen and neutrophilia, affects known to be mediated by proinflammatory cytokines. The objective of this study was to screen-culture supernatants from equine clinical isolates of S. equi and S. zooepidemicus for stimulation of mitogenic responses by horse peripheral blood mononuclear cells. Mitogenicity comparable to that of concanavalin A was detected in culture supernatants of S. equi strains but not in those of S. zooepidemicus. Mitogenicity...
Mitochondrial control region and 12S rRNA variation in Przewalski’s horse (Equus przewalskii).
Animal genetics    January 12, 1999   Volume 29, Issue 6 456-459 doi: 10.1046/j.1365-2052.1998.296380.x
Oakenfull EA, Ryder OA.Variation in the control region and the 12S rRNA gene of all surviving mitochondrial lineages of Przewalski's horse was investigated. Variation is low despite the present day population being descended from 13 individuals probably representing animals from three different regions of its range. Phylogenetic comparison of these sequences, with sequences for the domestic horse, does not resolve the ancestral status of either horse.
Pressure and temperature dependence of enantioselective excited-state quenching of chiral Tb(III) and Eu(III) tris(pyridine-2,6-dicarboxylate) chelates by various C-type ferricytochromes.
Enantiomer    October 23, 1998   Volume 3, Issue 2 95-102 
Meskers SC, Dekkers HP.For mitochondrial ferricytochrome c from horse, cow and tuna and for bacterial cytochrome c-550 from Paracoccus versutus, the pressure and temperature dependence of their quenching of racemic Tb(DPA)3(3-) and Eu(DPA)3(3-) (DPA = pyridine-2,6-dicarboxylate) luminescence in aqueous solution is investigated. Of these energy transfer reactions the activation volumes (delta V#) and energies (Ea) are determined for the ranges P = 0-3 kbar and T = 15-40 degrees C. For the lambda enantiomers of Tb(DPA)3(3-) and Eu(DPA)3(3-), delta V# and Ea are almost the same for all proteins: 0.4 < or = delta V# < o...
Carboxymethylated phosphatidylethanolamine in mitochondrial membranes of mammals–evidence for intracellular lipid glycoxidation.
European journal of biochemistry    September 17, 1998   Volume 255, Issue 3 685-689 doi: 10.1046/j.1432-1327.1998.2550685.x
Pamplona R, Requena JR, Portero-Otín M, Prat J, Thorpe SR, Bellmunt MJ.The non-enzymatic modification of aminophospholipids with lipoperoxidation-derived aldehydes and glycoxidation-derived products have been reported previously. However, it remains unknown whether intracellular membranes are damaged by these glycoxidation-derived products. To investigate this issue, we tested whether aminophospholipids from mitochondrial membranes are damaged by glycoxidative stress the mitochondrion being identified as the major site of reactive-species production in the cell. We have used a selected-ion-monitoring/gas-chromatography/mass-spectrometry assay for carboxymethyleth...
Skeletal muscle adaptations to prolonged training, overtraining and detraining in horses.
Pflugers Archiv : European journal of physiology    June 30, 1998   Volume 436, Issue 3 391-397 doi: 10.1007/s004240050648
Tyler CM, Golland LC, Evans DL, Hodgson DR, Rose RJ.Thirteen standard-bred horses were trained intensively for 34 weeks and detrained for 6 weeks to study skeletal muscle adaptations to prolonged training, overtraining and detraining. Training included endurance (phase 1, 7 weeks), high-intensity (phase 2, 9 weeks) and overload training (OLT) (phase 3, 18 weeks). During phase 3, horses were divided into two groups, OLT and control (C), with OLT horses performing greater intensities and durations of exercise than C horses. Overtraining was evident in OLT horses after week 31 and was defined as a significant reduction in treadmill run time in res...
Cryopreservation of equine embryos with glycerol plus sucrose and glycerol plus 1,2-propanediol.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 88-93 doi: 10.1111/j.2042-3306.1997.tb05109.x
Ferreira JC, Meira C, Papa FO, Landin e Alvarenga FC, Alvarenga MA, Buratini J.Six or 7-day-old equine embryos were divided into 4 groups; Group 1, n = 15, Day 7 embryos destined for immediate transfer; Group 2, n = 15, Day 6 embryos destined for deep-freezing with glycerol plus sucrose as cryoprotectant; Group 3, n = 10, Day 6 embryos destined for deep-freezing with glycerol plus 1,2-propanediol as cryoprotectant and Group 4, n = 3, fresh embryos destined for ultrastructural analysis. All the frozen/thawed embryos were transferred to recipient mares, except 3 embryos in Group 3 that were subjected to ultrastructural analysis. After thawing the cryoprotectants were remov...
Skeletal muscle histology and biochemistry of an elite sprinter, the African cheetah.
Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology    December 24, 1997   Volume 167, Issue 8 527-535 doi: 10.1007/s003600050105
Williams TM, Dobson GP, Mathieu-Costello O, Morsbach D, Worley MB, Phillips JA.To establish a skeletal muscle profile for elite sprinters, we obtained muscle biopsy samples from the vastus lateralis, gastrocnemius and soleus of African cheetahs (Acinonyx jubatus). Muscle ultrastructure was characterized by the fiber type composition and mitochondrial volume density of each sample. Maximum enzyme activity, myoglobin content and mixed fiber metabolite content were used to assess the major biochemical pathways. The results demonstrate a preponderance of fast-twitch fibers in the locomotor muscles of cheetahs; 83% of the total number of fibers examined in the vastus laterali...
An introduction to mammalian interspecific hybrids.
The Journal of heredity    November 5, 1997   Volume 88, Issue 5 355-357 doi: 10.1093/oxfordjournals.jhered.a023117
Short RV.Haldane's law states that in interspecific hybrids, it is the heterogametic sex that is likely to be absent, rare, or sterile. In mammals, there is increasing evidence to suggest that this may be due to the high mutation rate of male sex-determining genes on the Y chromosome. The mule, humanity's first successful attempt at genetic engineering, provides some support for this concept. Interspecific hybrids may also shed new light on the importance of the maternal transmission of mitochondrial DNA and the phenomenon of genomic imprinting.
Glyceraldehyde 3-phosphate dehydrogenase is bound to the fibrous sheath of mammalian spermatozoa.
Journal of cell science    August 1, 1997   Volume 110 ( Pt 15) 1821-1829 doi: 10.1242/jcs.110.15.1821
Westhoff D, Kamp G.Evidence is provided that the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase is covalently linked to the fibrous sheath. The fibrous sheath is a typical structure of mammalian spermatozoa surrounding the axoneme in the principal piece of the flagellum. More than 90% of boar sperm glyceraldehyde 3-phosphate dehydrogenase activity is sedimented after cell disintegration by centrifugation. Detergents, different salt concentrations or short term incubation with chymotrypsin do not solubilize the enzyme, whereas digestion with trypsin or elastase does. Short term incubation with trypsin...
Assessment of viability and mitochondrial function of equine spermatozoa using double staining and flow cytometry.
Theriogenology    July 15, 1997   Volume 48, Issue 2 299-312 doi: 10.1016/s0093-691x(97)84077-0
Papaioannou KZ, Murphy RP, Monks RS, Hynes N, Ryan MP, Boland MP, Roche JF.An objective double-staining method was developed to evaluate viability and mitochondrial function of stallion spermatozoa using flow cytometry. Sperm viability was assessed by propidium iodide (PI) exclusion, and mitochondrial function was measured by the intensity of rhodamine 123 (R123) fluorescence. Flow cytometry estimates of sperm viability measured by PI were equivalent (P > 0.05) to estimates made using Hoechst 33258 stain and fluorescent microscopy (% dead: 25 +/- 2.4 vs 21.5 +/- 3.5). The use of both PI and R123 was validated by addition of various proportions of freeze-shocked (m...
Persistent hyperammonemia in two related Morgan weanlings.
Journal of veterinary internal medicine    July 1, 1997   Volume 11, Issue 4 264-266 doi: 10.1111/j.1939-1676.1997.tb00101.x
McCornico RS, Duckett WM, Wood PA.Persistent hyperammonemia was diagnosed in 2 Morgan fillies with clinical signs that developed early in the postweaning period. Diagnostic evaluation, including routine serum chemistries, CBC, liver biopsy, hepatic ultrasonography, liver function test, and necropsy findings did not support a toxic, developmental, or infectious cause. Abnormal serum amino acid and urine orotic acid concentrations suggest that the foals may have had an inherited disorders described in humans as hyperornithinemia, hyperammonemia, and homocitrullinuria (HHH) syndrome. The disorder is thought to be caused by a defe...
Protonophoric activity of NADH coenzyme Q reductase and ATP synthase in coupled submitochondrial particles from horse platelets.
Biochemical and biophysical research communications    June 27, 1997   Volume 235, Issue 3 469-473 doi: 10.1006/bbrc.1997.6807
Baracca A, Bucchi L, Ghelli A, Lenaz G.A method to prepare coupled submitochondrial particles from horse platelets is described. The method allowed us to study the protonophoric activities of both complex I and complex V following the fluorescence quenching of the monoamine 9-amino-6-chloro-2 methoxyacridine (ACMA), a probe highly sensitive to the generation of a transmembrane delta pH. We carried out a kinetic analysis of each enzyme complex studying the proton translocation and the electron transfer activities of complex I as well as the proton translocation and the ATP hydrolytic activities of complex V. A micromethod to prepare...
The effects of ischemia and reperfusion on mucosal respiratory function, adenosine triphosphate, electrolyte, and water content in the ascending colon of ponies.
Veterinary surgery : VS    May 1, 1997   Volume 26, Issue 3 172-181 doi: 10.1111/j.1532-950x.1997.tb01481.x
McAnulty JF, Stone WC, Darien BJ.The purpose of this study was to examine the effects of ischemia and reperfusion on the biochemical integrity of equine colonic mucosa to assess the relative roles of ischemic- and reperfusion-induced damage. Methods: Two hours of no-flow ischemia experimentally induced by 720 degrees counterclockwise ascending colon volvulus followed by 2 hours reperfusion after derotation. Methods: Ten ponies. Methods: Ascending colon biopsies were obtained every hour for measurement of mucosal adenosine triphosphate (ATP), water, sodium, and potassium content. Additional samples were homogenized for assay o...
Oxidative energy metabolism in equine tendon cells.
Research in veterinary science    March 1, 1997   Volume 62, Issue 2 93-97 doi: 10.1016/s0034-5288(97)90127-2
Birch HL, Rutter GA, Goodship AE.Hypoxia has been suggested as a possible cause of tissue degeneration and subsequent rupture in equine tendons. To determine whether low oxygen tension is likely to be detrimental to tendon cell function, experiments were designed to investigate oxidative energy metabolism in freshly isolated and cultured equine tendon cells. Freshly isolated tenocytes and cultured fibroblasts possessed activities of the mitochondrial enzyme citrate synthase similar to those of other mammalian cells, with well defined oxidative metabolism. D-[6(-14)C]-glucose oxidation was measurable in both freshly isolated a...
Myoglobin content and oxygen diffusion: model analysis of horse and steer muscle.
The American journal of physiology    December 1, 1996   Volume 271, Issue 6 Pt 1 C2027-C2036 doi: 10.1152/ajpcell.1996.271.6.C2027
Conley KE, Jones C.We test the hypothesis that myoglobin is important for O2 supply near the oxidative capacity of muscle. This hypothesis is evaluated with a simple model that incorporates the properties of heart and skeletal muscle tissue taken from steers and horses exercising at their maximum O2 consumption rate. These tissue samples allowed us to set the bounds on oxidative demand and O2 flux from red blood cells to the core of the muscle fiber, to estimate the blood and tissue capacities for O2 diffusion, and to define the capillary blood PO2 driving this O2 flux. A model combining blood convection with ti...
Studies into aromatase activity associated with fetal allantochorionic and maternal endometrial tissues of equine placenta. Identification of metabolites by gas chromatography mass spectrometry.
The Journal of steroid biochemistry and molecular biology    November 1, 1996   Volume 59, Issue 3-4 281-296 doi: 10.1016/s0960-0760(96)00115-x
Marshall DE, Dumasia MC, Wooding P, Gower DB, Houghton E.Maternal endometrial and fetal allantochorionic tissues were separated manually from the placentae of seven healthy thoroughbred and three pony mares, ranging in gestational age from 100 to 318 days. The homogeneity of subcellular fractions prepared from these tissues was assessed initially using the marker enzymes, succinate dehydrogenase, NADPH cytochrome C reductase and lactate dehydrogenase for the mitochondrial, microsomal and cytosolic fractions, respectively. Light microscopy and histochemical analysis demonstrated that the separated fetal allantochorionic membrane, which is made up of ...
The complete mitochondrial DNA (mtDNA) of the donkey and mtDNA comparisons among four closely related mammalian species-pairs.
Journal of molecular evolution    November 1, 1996   Volume 43, Issue 5 438-446 doi: 10.1007/BF02337515
Xu X, Gullberg A, Arnason U.The nucleotide sequence of the complete mitochondrial genome of the donkey, Equus asinus, was determined. The length of the molecule is 16,670 bp. The length, however, is not absolute due to pronounced heteroplasmy caused by variable numbers of two types of repetitive motifs in the control region. The sequence of the repeats is (a) 5'-CACACCCA and (b) 5'-TGCGCGCA, respectively. The order of (a) and (b) can be expressed as {n[2(a)+(b)]+m(a)}. In 32 different clones analyzed the number of n and m ranged from 0 to 9 and 1 to 7. The two rRNA genes, the 13 peptide-coding genes, and the 22 tRNA gene...
PCR-RFLP analysis of the cytochrome b gene in horse mitochondrial DNA.
Animal genetics    October 1, 1996   Volume 27, Issue 5 359-363 doi: 10.1111/j.1365-2052.1996.tb00979.x
Ishida N, Hasegawa T, Oyunsuren T, Mukoyama H.The mitochondrial DNA sequence of cytochrome b gene in a Thoroughbred horse was determined. By comparing DNA sequences between the Thoroughbred and published sequence data (two horses and one Grevyi zebra), polymerase chain reaction (PCR) primers were designed for amplification of a 590 bp DNA fragment in the cytochrome b gene, and PCR-restriction fragment length polymorphism (RFLP) analysis was studied in 140 horses of six breeds using three restriction enzymes (AciI, BamHI, RsaI). Two morphs were found using each of the three enzymes. By combining three enzymes morphs, the 140 horses examine...
Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar lipid bilayer. II. Binding of cytochrome c to oxidase-containing cardiolipin/phosphatidylcholine membranes.
Biophysical journal    August 1, 1996   Volume 71, Issue 2 858-867 doi: 10.1016/S0006-3495(96)79287-1
Salamon Z, Tollin G.Complex formation between horse heart cytochrome c (cyt c) and bovine cytochrome c oxidase (cco) incorporated into a supported planar egg phosphatidylcholine membrane containing varying amounts of cardiolipin (CL) (0-20 mol%) has been studied under low (10 mM) and medium (160 mM) ionic strength conditions by surface plasmon resonance (SPR) spectroscopy. Both specific and nonspecific modes of cyt c binding are observed. The dissociation constant of the specific interaction between cyt c and cco increases from approximately 6.5 microM at low ionic strength to 18 microM at medium ionic strength, ...