Comparison, characterization, and identification of proteases and protease inhibitors in epididymal fluids of domestic mammals. Matrix metalloproteinases are major fluid gelatinases.

This research analyzes the presence and characteristics of certain proteins – proteases and protease inhibitors – in the fluids of the reproductive organs of various male livestock. It investigates their different types, concentrations, and locations within the organs and across species, revealing a resemblance in their distribution and suggesting a similar function in sperm development and organ flexibility.

Analysis and Findings

• The research involved an analysis of testicular and epididymal fluids from ram, boar, and stallion. This was done using one-dimensional and two-dimensional gelatin gel zymography, a technique used to detect and analyze proteins.
• The results showed between five and seven main gelatinolytic bands or zones where proteins were broken down. This suggested the presence of proteases, proteins that facilitate the break down of other proteins, in these zones.
• The study found that some of these proteases were inhibited by two substances, Ethylene Diamine Tetraacetic Acid (EDTA) and phenanthroline, indicating these were metal-dependent enzymes.
• The research investigated one of the key proteases, found in the fluids from the upper part of the epididymis. This protease showed a high sequence homology – a similarity in the order of its constituents – with the matrix-metalloproteinase-2 pro-form (pro-MMP-2), a protein crucial in the remodeling of tissues.

Identification of Moreover Proteases and Inhibitors

• The study identified various types of proteases present in the fluids, including MMP-2, MMP-3, and MMP-9, by using antibodies that can bind to these specific proteins. The regional distribution of these proteases was confirmed and they were all detected in the spermatic fluid of all three species studied.
• Another enzyme, acrosin, was also detected in the fluids, yet the researchers indicated that it didn’t account for the total serine protease activity. Serine proteases are a group of enzymes with a multitude of roles, like digestion or immune response. Acrosin was speculated to be released by dead sperm cells.
• The research also discovered the presence of certain proteins – protease inhibitors – which act against proteases. These were detected in the fluids of the reproductive organs of all three species. In particular, the protesease inhibitor alpha(2)-macroglobulin was identified as being responsible for binding most of the enzyme acrosin, and TIMP-2, another inhibitor, was identified in certain regions of the organ in all three species.

Implication of the Study

• The similarity in the types and distribution of proteases and inhibitors across species suggests that these proteins probably have a common function, possibly in the maturation of sperm cells or in the adaptability of the organ itself.