Dérivés dansylés des acides aminés

The severed activation segment of porcine pancreatic procarboxypeptidase A is a powerful inhibitor of the active enzyme. Isolation and characterisation of the activation peptide

The activation peptide of the monomeric procarboxypeptidase A from porcine pancreas was isolated by means of controlled trypsin digestion of the proenzyme followed by ion-exchange chromatography under dissociating conditions (7 M urea). The molecular weight of the isolated peptide was estimated to be around 11500-12000 (corresponding to approx. 100-103 residues) as judged by SDS electrophoresis and amino acid analysis, a figure that agrees with the differences between the corresponding values for procarboxypeptidase A and carboxypeptidase A (peptidyl-L-amino acid hydrolase, EC 3.4.17.1). The activation peptide has a high content of hydrophobic and acidic amino acids, and lacks cysteine. A remarkable feature is the strong competitive inhibitory action of the peptide on both porcine and bovine pancreatic carboxypeptidase A activity, with a Ki in the nanomolar range, and its null ability to inhibit porcine pancreatic carboxypeptidase B (EC 3.4.17.2). The above properties, and the fact that the peptide has the same N-terminal residue (lysine) as the parent procarboxypeptidase A, suggest that the isolated peptide contains most (if not all) of the activation segment of the proenzyme.

Fractionation and structure of several hydroxyproline-containing urinary peptides, with special reference to some 3-hydroxyproline-containing peptides

After a preliminary separation of the hydroxyproline-containing peptides on Biogel P 2, the largest peptides are fractionated on phosphocellulose and the smallest ones on QAE-Sephadex. The fractions obtained from QAE-Sephadex are subfractionated on a column of Dowex 50-M-82. The total number of hydroxyproline-containing peptides from human urine is not less than 78. Sixteen di, tri and pentapeptides have been purified, their N-terminal amino acids and amino acid compositions determined and a structure is proposed. 3 of these peptides contain 3-hydroxyproline and one of these 3 peptides probably originates from basement membrane collagen.

Primary structure of histone H2A from gonad of the sea urchin Psammechinus miliaris

The complete amino acid sequence (125 residues) of sea urchin histone H2A has been established by structural studies of peptides derived from tryptic and chymotryptic cleavage of the maleylated protein and from thermolysin cleavage of the intact protein. By comparison with calf homologous histone, the basic amino-terminal and carboxy-terminal parts of the protein show 11 substitutions and 4 deletions. The remainder of the sequence, mostly hydrophobic, is almost completely unchanged.

[Determination of the primary structure of alfalfa mosaic virus (strain S) coat protein. II. Complete sequence of the protein (author's transl)]

The alfalfa mosaic virus protein was submitted to the action of cyanogen bromide. Four peptides were isolated. Study of these peptides allowed us to determine the order. Then protein was submitted, after S-carboxymethylation or S-aminoethylation, to the action of different proteolytic enzymes: trypsin, chymotrypsin, thermolysin and papain. The peptides issued from these different hydrolysis were separated on Dowex 50 X4 and Dowex 1 X2, and their amino acid composition was determined. The use of classical methods of sequence determination, of mass spectrometry and for one case the use of a sequencer, lead to the obtention of the primary structure of all the tryptic peptides. The studies of chymotryptic, thermolytic and papainic hydrolysates, and of cyanogen bromide rupture, allowed us to isolate the overlapping peptides which were necessary for the reconstitution of the complete proteic chain.

Structure and morphogenesis of photosynthetic membranes. I. Is there a single basic peptide within Zea mays thylakoids?

We have previously given evidence for a physical heterogeneity among proteins from photosynthetic membranes of maize chloroplast [1]. About fifteen components have now been identified, differing in their molecular weights and also in their varying abilities to bind protochlorophyllide and chlorophyll [2]. In this paper, we show that all these proteins have very similar amino acid compositions. A detailed chemical comparison is made between, on one hand the mixture of all proteins and on the other the smallest component of molecular weight 10 000. All the features analysed (percent of non-proteic material, partial peptide maps, N and Cterminal ends and content of linked sugars) are the same in both cases. We conclude from these experiments that it is likely that all components are generated with the same basic peptide unit. This assertion seems to be confirmed by the fact that, after mild alkaline treatment, all the components are converted into the smallest one, as seen by electrophoresis. Thus, within the photosynthesizing membranes, there appears to be a basic structural protein unit, present in a form that is more or less "polymerized". This may account for most of the particular, and sometimes disturbing, properties so far described for this system. It is likely that such a peptide, or a similar one, would provide a framework for all photosynthesizing structures.