Bradykinin Amino acid sequence

Certain pentapeptides potentiate the contractile response of isolated guinea-pig ileum to bradykinin [4, 5], The effects on bradykinin potentiation of varying the amino-acid sequence in the pentapeptide were investigated [6]. Each of the five amino acids was regarded as a substituent. By constructing a particular scale from the physicochemical properties of the amino acids, the variation in amino-acid sequence in the pentapeptides can be quantitatively described [6, 7]. 

Kato, H. and Suzuki, T. 1971. Bradykinin-potentiating peptides from the venom of Agkistrodon halysblomhojfii. Isolation of five bradykinin potentiators and the amino acid sequences of two of them, potentiators B and C. Biochemistry 10, 972—980. 

Two attempts have been reported to predict the conformation of a polypeptide hormone by assembling the appropriate residues in their predicted conformation (63, 90). In this manner, the amino acid sequence of bradykinin was predicted to exist in a random coil conformation, with variation around the glycine bond, and with no interaction predicted between phenyl groups. As yet no experimental evidence confirms this prediction however, existing experimental evidence suggests that the prediction is reasonable (67-69). In the second study the conformation of gastrin tetrapeptide was predicted (90). 

Incubation of a protein fraction from blood plasma with trypsin gives rise to peptides with conspicuous biological effects. Pain, dilation of peripheral blood vessels, increased coronary flow and enhanced capillary permeability were observed on administration of these protein fragments [8]. In the early sixties the nonapeptide bradykinin and its precursors, kallidin and methionyl-kalUdin were isolated in pure form and their amino acid sequences determined soon after. 

Ladder Sequencing. Because plasma desorption mass spectra commonly reveal only molecular ions, it has become common to obtain amino acid sequences using carboxy or amino-peptidases to generate a mixture of truncated peptides whose mass differences correspond to the amino acid residues. One example of this is shown in Figure 4.15, in which bradykinin has been digested directly on the nitrocellulose foil with carboxypeptidase... 

A prominent rdle in kinin research has been played by synthetic chemists since Boissonnas and coworkers synthesized bradykinin in 1960, tefore the final amino acid sequence of the natural product had been established The investigation of kinins then entered a period of rapid growth. This growth is reflected in a number of symposia and reviews that have been devoted to this subject in recent years... 

Complete hydrolysis followed by amino acid analysis indicates a ratio of 3 Pro, 2 Phe, 2 Arg, and one each of Gly and Ser. Dednce the amino acid sequence of bradykinin. 

The amino acid composition of the peptide is (Arg, Gly, Phe, Pro, Ser). Treatment of bradykinin with the Edman reagent gives the PTC-derivative of arginine. Partial hydrolysis yields several fragments that include the following oligopeptides. What is the amino acid sequence of bradykinin ... 

Amino acid composition and amino acid sequence studies revealed that fraction I (panel 2) and fraction II (panel 3) were bradykinin and [hydroxyprolyl ] bradykinin, respectively. 

Bradykinin has a linear sequence of 9 amino acid residues, and all residues are necessary for agonist activity at the constitutively expressed B2-receptors. However, C-terminal deletion by enzymes including kininase I (EC.3.4.11.12), yields desArg ]BK (i.e. BKiJ.and [desArg JKO (i.e. KDi.s), and these metabolites are active at inducible Bj-receptors - but not at B2-receptors. In contrast, the parent molecules are very potent at Bj-receptors, but have relatively little activity at Bi-receptors. The stimulus for induction of B -receptors seems to be certain inflammatory mediators, notably cytokines. 

Its use with bradykinin and desmopressin (Zubarev et al., 1994), illustrated as a case study below, shows the benefits of MS sequence analysis. The latter peptide, desmopressin ( Minirin , a neurohypophysial hormone analogue), involves a disulphide link and a C-terminal amide, as well as a non-coded amino-acid residue (Mpa = mercaptopropionic acid) and these features can be identified by chemical sequencing methods (Chapter 5) only with considerable effort. 

P. representing partial sequences of larger P. are represented by pladng the sequence numbers of the first and last amino acids in brackets after the trivial name, followed by the Greek root for the number of residues in the partial sequence, e.g. bradykinin-(3-9)-heptapeptide. 

Merrifield used this procedure to prepare a number of peptides. For example, he synthesized the nonapeptide bradykinin in 68% yield in only eight days, a remarkable feat at the time.The biological activity of the synthetic peptide was identical with that of the natural peptide. Merrifield was ultimately able to automate all the steps in his technique for solid-phase peptide synthesis and demonstrated its power by using a homemade machine to prepare bovine pancreatic ribonuclease, an enzyme that contains 124 amino acids. This synthesis proceeded in 17% overall yield and required 369 chemical reactions and 11,931 individual operations The synthetic ribonuclease had a specific activity that was 13-24% that of the native enzyme. The lower activity of the synthetic enzyme can probably be attributed to the fact that each coupling step did not proceed with 100% efficiency, so some polypeptides lacking one or more individual amino acids in the sequence were also produced. Because of their close similarity to ribonuclease, it was not possible to separate these polypeptides from the synthetic enzyme. 

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