N. Barkhudaryan et al., HIGH-MOLECULAR-WEIGHT ASPARTIC ENDOPEPTIDASE GENERATES A CORONARO-CONSTRICTORY PEPTIDE FROM THE BETA-CHAIN OF HEMOGLOBIN, FEBS letters, 329(1-2), 1993, pp. 215-218
Studying the influence of brain cathepsin D (EC 3.4.23.5) and high mol
ecular weight (HMW) aspartic endopeptidase (EC 3.4.23.-) on the proces
sing of hypothalamic calmodulin-binding coronaro-constrictory peptide
factors from the beta chain of globin it was found that only HMW aspar
tic endopeptidase generates the fragment 31-40 of the beta-chain of bo
vine hembglobin (Hb) by cleavage of the Leu30-Leu31 and Phe40-Phe41 bo
nds. Digestion of the beta-chain of globin was performed at 37-degrees
-C at an enzyme/substrate ratio of 1:80 at pH 3.5 using different time
s of incubation (from 4 h to 10 h). The resulting peptides were separa
ted by reversed-phase high-performance liquid chromatography (HPLC) an
d then identified by amino acid analysis and Edman degradation. The di
fferences in specificity and activity of these two brain aspartic prot
einases could be explained by their different structural features. Our
finding provides evidence for a different biological function of thes
e two enzymes. Data obtained give us reason to suppose that HMW aspart
ic proteinase probably can participate in the processing of the corona
ro-constrictory peptide in vivo by limited proteolysis of Hb or Hb-lik
e protein.