• Journal of the Korean Chemical Society
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• v.19 no.4
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• pp.246-251
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• 1975

A spectrophotometric assay technique is descriead for the measurement of free SH-groups in the enzyme reaction mixture. The method utilizes a new substrate, S-hippuryl-thioglycolyl-glycine(S-Hip-thioglycol-Gly) which is the basis for a convenient assay of angiotensin-converting enzyme and other dipeptidyl carboxypeptidases. This substrate contains an appropriately located thioester linkage that is hydrolyzed by the converting enzyme and other dipeptidyl carboxypeptidases. One of the products, thioglycolyl glycine, is readily measured by reaction with Ellman's reagent, 5,5'-dithio-bis-(2-nitrobenzoic acid), DTNB, to produce 5-thio-2-nitrobenzoic acid which has a strong absorption band at 410 nm. The method is sensitive (${\varepsilon}M = 1.36{\times}10^4$ at 412 nm) and can be applied as a continuous recording with DTNB present in the enzymatic reaction mixture.

• YAKHAK HOEJI
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• v.38 no.5
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• pp.530-543
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• 1994

To study the feasibility of transmucosal delivery of leucine enkephalin (Leu-Enk) and $[D-ala^2]$-leucine enkephalinamide (YAGFL), their degradation extents and pathways in various rabbit mucosa extracts were investigated by high performance liquid chromatography. The degradation of Leu-Enk and YAGFL was observed to follow the first-order kinetics. The degradation half-lives of Leu-Enk in the nasal, rectal and vaginal mucosal extracts were 1.62, 0.37 and 1.12 hrs and those of YAGFL were 30.55, 9.70 and 6.82 hrs, respectively, indicating Leu-Enk was degraded in a more extensive and rapid manner than YAGFL. But the mucosal and serosal extracts of the same mucosa showed the similar degradation rates for both pentapeptides. The degradation was most rapid in the neutral pH and increasing concentrations of substrates retarded the degradation rates. The maior hydrolytic fragments of Leu-Enk were Des-Tyr-Leu-Enk and tyrosine, indicating the enzymatic hydrolysis by aminopeptidases. However, the data also suggested endopeptidases such as dipeptidyl carboxypeptidase and dipeptidyl aminopeptidase could play some role in the degradation of Leu-Enk. On the other hand, the hydrolytic fragments of YAGFL in all the mucosa extracts were mainly Tyr-D-Ala-Gly and Phe-Leu-Amide, demonstrating the hydrolytic breakdown by endopeptidases. The degradation pathways were further explored by concomitantly determining the formation of smaller metabolites of primary hydrolytic fragments of Leu-Enk and YAGFL in the mucosa extracts.

• Applied Biological Chemistry
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• v.49 no.4
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• pp.293-297
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• 2006

Angiotensin converting enzyme(ACE) is a zinc-containing dipeptidase widely distributed in mammalian tissues and is thought to play a significant role in blood pressure regulation by hydrolyzing angiotensin I to the potent vasoconstrictor, angiotensin II. Recently, the presence of ACE in pig ovary was reported and the ACE from pig kidney was isolated and characterized. However no nucleotide sequence of the ACE gene from pig is yet known. We report here the cloning of the ACE cDNA from pig kidney by using the reverse transcriptase-polymerase chain reaction. The complete amino acid sequence deduced from the cDNA contains 1309 residues with a molecular mass of 150 kDa, beginning with a signal peptide of 33 amino acids. Amino acid sequence analysis showed that pig kidney ACE is also probably anchored by a short transmembrane domain located near the C-terminus. This protein contains a tandem duplication of the two homologous amino acid peptidase domain. Each of these two domains bears a putative metal-binding site (His-Glu-Met-Gly-His) identified in mammalian somatic ACE. The alignment of pig ACE amino acid sequence with human, rabbit, and mouse reveals that both two domains have been highly conserved during evolution.