Angiotensin I converting enzyme of calf lung. Method of assay and partial purification

Abstract

A continuous ultraviolet spectrophotometric assay for angiotension I converting enzyme has been developed utilizing amino-terminal-blocked tripeptides as substrates. Z-Phe(N02)-His-Leu, Z-Phe(N02)-Gly-Gly, and Hip(NC>2> Gly-Gly have been synthesized as effective substrates for angiotensin I converting enzyme. These substrates have facilitated the partial purification and characterization of angiotensin I converting enzyme from calf lung. This enzyme was

Angiotensin converting enzyme-inhibitory activity of peptides isolated from Manchego cheese. Stability under simulated gastrointestinal digestion

“…In a similar manner, peptide KKYNVPQL (a s1 -CN f(102-109)) exhibited a 10 fold greater inhibitory activity than KKYNVPQ (a s1 -CN f(102-108)) (IC 50 values 77.1 and 716.9 mm, respectively) which might be also caused by the presence of leucine as the C-terminal residue. Moreover, it is known that ACE only binds weakly with competitive peptide inhibitors that have penultimate proline residues (Cushman et al, 1973) (as occurs in KKYNVPQ) while, on the other hand, the presence of proline as antepenultimate residue (as occurs in KKYNVPQL) appears to enhance binding (Stevens, Micalizzi, Fessler, & Pals, 1972;Rohrbach, Williams, & Rolstad, 1981). Therefore, both the position of proline and the presence of leucine as the C-terminal residue in KKYNVPQL could explain the more potent activity exhibited by this peptide.…”

Fluorimetrie Determination of Dipeptidyl Carboxypeptidase

“…Angiotensin I, however, is hydrolyzed at a much lower rate [12,15] and, according to Stevens et al [15], hippuryl-His-Leu is hydrolyzed at 20% of the rate observed with Z-Phe-His-Leu.…”

“…It is now admitted that the enzyme catalyzing the conversion of angio tensin I to the potent vasoconstrictor angiotensin II is, in fact, a dipeptidyl carboxypeptidase (EC 3.4.15.1) capable of releasing C-terminal dipeptides from such substrates as bradykinin, angiotensin I and various shorter synthetic peptides [3,8,12,15,16]. The enzyme occurs in particularly high concentrations in lungs [13] and sperm [4,6], It is of special interest in view of the role played by angiotensin II in renal hypertension.…”

“…Dipeptidyl carboxypeptidase activity has been measured by a variety of methods: bioassay [1,2] or radioimmunoassay [10,11] of angiotensin II after incubation with angiotensin I, radioassay of L-histidyl-L-leucine (HisLeu) released from labelled angiotensin I [9], and methods using colorimetry [7], spectrophotometry [3,15] or fluorimetry [12] as the measuring technique.…”

Whey Proteins as Source of Bioactive Peptides Against Hypertension

“…Trp, Tyr, Phe and Pro) at the C-terminus, and shows poorer affinity to substrates containing dicarboxylic amino acids in the final position, or those that have a Pro residue in the one before the last position. However, presence of Pro as the last residue [258], or in the third position from the terminus [259] favors binding of peptide to enzyme, in much the same way as when Leu appears in the last position [260,261].…”