Occurrence of Leu-Lys-bradykinin and histidine-rich peptide in high-molecular-weight kininogen isolated from horse plasma.

The research article discusses the identification of Leu-Lys-bradykinin and histidine-rich peptide in high-molecular-weight kininogen isolated from horse plasma. Three new peptides were produced when horse plasma high-molecular-weight kininogen incubated with purified plasma kallikrein.

Objective of Research

• The main aim of the research was to investigate high-molecular-weight kininogen in horse plasma under certain conditions and identify any new peptides formed as a result.

Research Methodology

• Scientists incubated high-molecular-weight kininogen isolated from horse plasma with plasma kallikrein, a potent plasma protein enzyme, to observe any biochemical reactions.
• The process resulted in the formation of three new peptides, named fragment 1, fragment 1.2, and fragment 2, along with a hormone that affects blood vessels known as bradykinin.
• Performing characterisation studies revealed that fragment 2 contains a high level of histidine – an essential amino acid.
• The researchers identified 11 histidine residues out of the total 48 in fragment 2, indicating a histidine-rich region in horse high-molecular-weight kininogen.

Research Findings

• The research proved the existence of a histidine-rich region in horse high-molecular-weight kininogen. This region is similar to one previously identified in bovine high-molecular-weight kininogen, pointing to potential evolutionary similarities between species.
• The team also discovered a new derivative of kinin, Leu-Lys-bradykinin, within the horse high-molecular-weight kininogen. This derivative was not known prior to the study, leading to new understanding within the peptide chemistry field.

Significance of Research

• The findings contribute to the scientific understanding of complex proteins and peptides and how they function within biological organisms.
• The discovery of the Leu-Lys-bradykinin kinin derivative and the histidine-rich region provides valuable knowledge to the biochemical and veterinary fields, which can be used to discover or create new treatments.