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Porcine secretin is a heptacosapeptide with the amino acid sequence His-Ser-Asp-Gly-Thr- Phe -Thr- Ser -Glu -Leu -Ser -Arg -Leu -Arg -Asp-Ser -Ala -Arg -Leu -Gin -Arg -Leu -Leu-Gln-Gly-Leu- Va1NH2. Fourteen of its twenty-seven amino acids occur in the same position as they do in porcine glucagon. [ABSTRACT FROM AUTHOR]

This paper is the fifth of a series devoted to the primary structure of the bovine β-casein A². The first two communications dealt with the isolation, analysis and positioning in the peptide chain of the tryptic and “CNBr” peptides [1,2]. The last two described the sequence of 65 residues from the carboxyl-terminus and of 32 residues from the amino-terminus [3,4]. We report here a partial sequence which includes 156 residues (out of the 209 residues of the β-casein A²) exactly positioned in the peptide chain. Two segments including 53 residues (from position 36 to 68 and from 73 to 92) remain to be analyze. In addition to the tryptic and “CNBr” peptides originating from β-casein A², two peptides issued from a tryptic digest of β-casein B were used as starting material. The position of the substitution His→Gln which differentiates the β-casein A² from the β-casein A³, already given in a preliminary communication [5], is indicated, as it is for the substitution Ser→Arg which represents one of the two differences occurring between the β-casein A² and the β-casein B. Four of the five phosphorus atoms of the β-casein A² have been previously located in the NH2-terminal tryptic peptide [4]. The fifth has been located at position 35. All the phosphorus atoms of the β-casein A² occur as phosphoserine. The complete structure of the β-casein A² will be given and discussed in the next and last paper. [ABSTRACT FROM AUTHOR]

Using automated stepwise Edman degradation of suitable overlapping peptides, the complete amino acid sequence of the 268 residue peptida α1-CB7 from calf skin collagen was determined. The preparation and ordering of the chymotryptic, tryptic and thermolytic peptides is described in the preceding paper. As shown previously for other peptides from the helical region of collagen, glycine appears in every third position and proline is present in high amount. Hydroxylation of proline to 4-hydroxyproline and lysine to hydroxylysine only occurred in the Y position of the tripeptide unit Gly-X-Y. Non-random distribution of other amino acids between the X and Y positions was also observed. [ABSTRACT FROM AUTHOR]

The primary structure of the light chain of myeloma protein Car was studied. The light chain was fully reduced and alkylated with iodo[14C]acetic acid and digested with trypsin. The tryptic peptides were purified and sequenced. Peptides that overlapped the tryptic peptides were isolated from a peptic digest. The object was primarily to sequence the variable part of the chain, whereas the peptides of the constant part were only partially sequenced. The amino acid sequence of the variable part coincides with the basic sequence of the κIb subgroup, except for few substitutions. Some of the above-mentioned substitutions are unique and some have been observed already in other κI chains. Two unusual features of this light chain are the presence of carbohydrate covalently bound to the asparagine residue occupying position 28 and the deletion of one amino acid at position 95. [ABSTRACT FROM AUTHOR]

The porcine anti-dinitrophenyl antibody was subjected to affinity labeling by m-nitrobenzenediazonium fluoroborate. From the S-sulfo derivative of the labeled antibody light (λ and ...) and heavy chains were isolated. It was found by spectral analysis of the polypeptide chains that the m-nitrobenzenediazonium reagent labeled tyrosine residues. In the light chains 10% molecules, in the heavy chains 21% molecules were labeled. Tryptic digest of labeled λ-chains was resolved by gel chromatography. The label was found to be distributed in two peasks at a ratio of 7: 3. From the labeled peptides of the tryptic digest shorter peptides were prepared by hydrolysis with subtilisin and purified by gel chromatography, paper chromatography and affinity chromato- labeled se peptides with known sections of the amino acid sequence of the λ-chains of porcine nonspecific immunoglobulin showed that the main portion of the label is attached to the tyrosine in position 33, s lesser portion to the tyrosine in position 93. [ABSTRACT FROM AUTHOR]

From the tryptic hydrolyzate of pig immunoglobulin &kappa-chains 6 cystine-containing fragments were isolated. Amino acids analysis showed that they contained 37-70 amino acid residues and were of a variable nature. There exists a linear relationship between the specific electrical charge of the fragment and the ionic strength of the buffer by which the fragment is eluted from a column of QAE-Sephadex. Fragments, the disulfide bond of which was split by oxidative sulfitolysis, were split by thermolysin and the hydrolyzates were compared by the method of peptide maps. All the maps of fragments tested contained the peptide Ile-ThrSerCysSSO3-Arg (where CysSSO3 = S-sulfo-cysteine) which represents the vicinity of the half-cystine 24 of pig κ-chains, as shown by us previously. The nature of the peptide maps indicates that the individual fragments originate in the same section of the primary structure of the N-terminal half of the κ-chains. Each of the isolated fragments was a mixture of variants with an identical specific charge but with some amino acid replacements. [ABSTRACT FROM AUTHOR]

The section which represents a part of a larger fragment of the variable part of pig immunoglobulin λ-chains is constituted by two peptides (18 residues and 4 residues)of variable character. These peptides were fractionated and their amino acid sequence determined. At certain positions two to four different amino acids were found. There is a close relation between the found amino acid sequence ... and the amino acid sequence of the corresponding region of human type L Bence-Jones proteins. [ABSTRACT FROM AUTHOR]

Various workers have interpreted their data on the rates of alkaline denaturation of ferrihemoglobin either as a consequence of the presence of two distinct species or as a result of two consecutive first order steps involving an intermediate. Our results with a chromatographically purified homogeneous sample indicate that the rate of alkaline denaturation support the latter hypothesis. The rates of denaturation of ferrihemoglobins A, S and C under the same conditions differ, and it is concluded that the amino acid sequence of the ferrihemoprotein plays a significant role in the conformational stability of the molecule. [ABSTRACT FROM AUTHOR]

The complete amino-acid sequence of cytochrome c from Ginkgo biloba L. (Maidenhair tree) has been determined on 0.5 µmol protein; chymotryptic and tryptic peptides were analysed by the dansyl-Edman method. The molecule consists of a single polypeptide chain of 113 amino-acid residues and is homologous with the other plant cytochrome-c sequences which have been determined [1]. The additional residues present as compared to other plant cytochromes c are at the C. terminus of the protein. Residue 59 was glycine; previously all mitochondrial cytochromes c have invariant alanine in this position. Two residues of the unusual amino acid ε-N-trimethyl-lysine are present in the protein. [ABSTRACT FROM AUTHOR]

The conformational properties of the basic pancreatic trypsin-inhibitor have been studied using both physical and chemical techniques. The structural properties of this mini-protein are quite unusual. The folded conformation remains unaltered at 77 °C and pH 2.1 or in 6 M guanidine-HCl at pH 7.5. The selective cleavage [22] of the disulfide bridge Cys14-Cys38 reduces considerably the stability of the inhibitor towards heat or guanidine-HCl. A conformational study of the carboxamidomethyl, carboxymethyl, and aminoethyl derivatives of the inhibitor has been carried out after partial reduction and modification of Cys14 and Cys38 by iodoacetamide, iodoacetic acid, and ethyleneimine. There exist three folded isometric forms of the inhibitor between pH 1 and 11. Form I is the most stable form; it exists near neutral pH. It is extremely thermostable and remains folded in 6 M guanidine-HCl. Form II is stable below pH 1.5-2; its transition temperature is 81 °C. Form III is predominant at pti 10-11 at 20 °C. A detailed analysis of the conformational isomers I, II and III has been carried out with the carboxamidomethylated inhibitor. Both physico-chemical and chemical data indicate that the acidic conformational change I ... II is dependent upon the ionisation of a buried carboxylate which may be the side-chain of Glu7. The alkaline isomerisation I ... III is induced by the unmasking of the α-ammonium of the N-terminal arginine residue. The apparent pK of the group is 9.4 at, 25 °C. Acetylation of the α-amino group stabilizes a form very similar to III and prevents the formation of form I at neutral pH. [ABSTRACT FROM AUTHOR]

A methionine-containing tryptic peptide from acetamidinated human carbonic anhydrase B has been isolated. This peptide has been shown to bridge a previously known carboxyl-terminal fragment prepared by CNBr degradation with the rest of the enzyme molecule. Sequence studies on the methionine-containing peptide have extended the previous knowledge of the carboxyl-terminal sequence of the enzyme. Corresponding bridge peptides from human carbonic anhydrase C and acetamidinated bovine carbonic anhydrase B have also been isolated and their amino acid compositions have been determined. [ABSTRACT FROM AUTHOR]

A method for amino acid analysis by double isotope labeling has been developed using ⊃3H-labelled dansyl chloride, and 14C-labelled amino acids as internal standards. As little as 20 pmol of an amino acid can be accurately measured by this method. The amino acid compositions of several peptides, determined using about 50pmol peptide, are reported and compared with the results obtained using conventional high-sensitivity ion-exchange chromatography. The correspondence is very good. The amino acid composition of a tryptic peptide containing the active site disulphide bridge of the lipoamide dehydrogenase component of the pyruvate dehydrogenase multienzyme complex of Escherichia coli has been shown to be identical to that of the corresponding peptide from the 2-oxoglutarate dehydrogenase complex of the same organism. This result is consistent with the view that the lipoamide dehydrogenase components of both complexes have a common amino acid sequence. [ABSTRACT FROM AUTHOR]

Chloroform-soluble proteins have been isolated free from phosphatides from rat liver mitochondria, microsomes and cytosol by chromatography on Sephadex LH-20 columns. The amino acid composition of the chloroform-soluble and insoluble proteins has been estimated. The chloroform-soluble proteins from mitochondria and cytosol have a higher content of hydrophobic and a lower content of acidic amino acids compared to the corresponding chloroform-insoluble proteins. No marked differences were found between chloroform-soluble and insoluble proteins from microsomes. In contrast to the acidic chloroform-insoluble proteins, all chloroform-soluble proteins are basic. From the amino acid composition the amount of chloroform-soluble proteins has been estimated. Mitochondrial membranes contain 1.6%, mitochondrial matrix proteins less than 0.025%, microsomes 3.0% and the cytosol 0.15% from total proteins. The molecular weight distribution of chloroform-soluble proteins synthesized in mitochondria has been measured by gelelectrophoresis. The molecular weights range from about 7000 to 30000. The turnover of chloroform-soluble proteins from mitochondria and cytosol is higher than from the corresponding chloroform-insoluble proteins. A part of mitochondrial chloroform-soluble proteins (about 30%) is synthesized within the mitochondria. [ABSTRACT FROM AUTHOR]