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K B Reid

Publications and source records attributed to K B Reid.

194 records · Page 11Linked to original sources
PubMed1974

A collagen-like amino acid sequence in a polypeptide chain of human C1q (a subcomponent of the first component of complement).

1. A partial amino acid sequence of 95 residues of the 191 residues in the oxidized A chain of human subcomponent C1q was determined. The partial nature of the sequence is because one overlapping peptide is missing in the proposed sequence, also the proof of some of the overlapping peptides depends partly on their amino acid composition and not on their complete sequence. 2. This region of the A chain contained a repeating sequence of glycine-X-Y (where X is often proline and Y is often hydroxyproline) for 78 residues. 3. The five hydroxylysine residues and the five hydroxyproline residues present in the oxidized A chain were all in these 78 residues and only in the Y position of the repeating sequence. 4. Prolonged collagenase digestion of the oxidized A chain yielded a large, apparently C-terminal, peptide which contained most of the non-collagenous sequences present in the chain. 5. It is concluded that there is a collagen-like region in the A chain of subcomponent C1q which constitutes most of the N-terminal half of the chain and that similar collagen-like regions will be found in the B and C chains.

Amino Acid Sequence↗
PubMed1974

Studies on the structure and activity of rabbit Clq (a subcomponent of the first component of complement).

1. The subunit structure of rabbit subcomponent C1q was examined in a previous publication (Reid et al., 1972). The present paper describes some aspects of the structure of the polypeptide chains derived from the molecule. 2. The three polypeptide chains, produced by performic oxidation, of rabbit subcomponent C1q were isolated by ion-exchange chromatography in 8m-urea on DEAE-cellulose. 3. Each chain was found to contain 15-18% glycine and significant amounts of the amino acids hydroxyproline and hydroxylysine. 4. By means of collagenase digestion it was shown that all three chains of rabbit subcomponent C1q contain collagen-like sequences of amino acids which constitute about 40% of each chain. 5. By use of carboxypeptidase A it was established, indirectly, that the collagen-like sequences, in one of the chains, are probably located near, or at, the N-terminal end of the chain. 6. Collagenase digestion and heating at 52 degrees C (but not at 49 degrees C) caused rapid loss of native rabbit subcomponent C1q haemolytic activity.

Amino Acids↗
PubMed1972

Isolation and characterization of C1q, a subcomponent of the first component of complement, from human and rabbit sera.

1. C1q, a subcomponent of the first component of complement, has been isolated, in a haemolytically active and soluble form, by ion-exchange chromatography and gel filtration, from human and rabbit sera. Yields ranged from 10 to 25mg/litre of serum and the activity of final preparations was consistently in the range 5x10(3)-15x10(3) C1qH(50) units/mg. 2. The molecular weights of human and rabbit subcomponent C1q were 409600 and 417600, as determined by sedimentation equilibrium studies. 3. Subcomponent C1q from both species was shown to be composed of non-covalently linked subunits of approximately 57000 molecular weight as determined by gel-filtration or sedimentation equilibrium studies in 5.3m-guanidinium chloride. Reduction or oxidation of human and rabbit subcomponent C1q yielded three chains each having a molecular weight of approximately 23000 and which differed slightly in amino acid composition but markedly in carbohydrate content. The oxidized chains were separated, on a preparative scale, by ion-exchange chromatography in 8m-urea on DEAE-cellulose. 4. Both human and rabbit subcomponent C1q contained hydroxyproline, hydroxylysine, a high percentage of glycine and approximately 8% carbohydrate. Glutamic acid and aspartic acid were the free N-terminal amino acids of human subcomponent C1q whereas only serine was found in rabbit subcomponent C1q. 5. Collagenase digestion of human or rabbit subcomponent C1q caused a rapid loss of haemolytic activity which correlated with the breakdown of collagenous regions in the molecule.

Amino Acids↗
PubMed1968

Isolation and a partial amino acid sequence of insulin from the islet tissue of cod (Gadus callarias).

1. Insulin has been isolated by gel filtration and ion-exchange chromatography from extracts of the discrete islet tissue of cod. The final preparation yielded a single band on electrophoresis at two pH values. The biological potency was 11.5 international units/mg. in mouse-convulsion and other assay procedures. 2. Glycine and methionine were shown to be the N-terminal amino acids of the A and B chains respectively. An estimate of the molecular weight together with amino acid analyses indicated that cod insulin, like the bovine hormone, consists of 51 amino acid residues. In contrast, the amino acid composition differs markedly from bovine insulin. 3. Oxidation of insulin with performic acid yielded the A and B peptide chains, which were separated by ion-exchange chromatography. Sequence studies on smaller peptides isolated from enzymic digests or from dilute acetic acid hydrolysates of the two chains have established the sequential order of 14 of the 21 amino acid residues of the A chain and 25 of the 30 amino acid residues of the B chain.

Amino Acid Sequence↗
PubMed1968

Biosynthesis of an insulin precursor by islet tissue of cod (Gadus callarias).

1. At 15 degrees , slices of cod islet tissue incorporated [U-(14)C]proline into proteins soluble in acid-ethanol at a linear rate for 6hr. 2. Initially, all the radioactivity was associated with a polypeptide that had a molecular weight of about 10000 and was appreciably more basic than cod insulin. After 1hr. there was also a significant and progressive increase in the radioactivity of insulin and of fractions intermediate in molecular size and basicity between the polypeptide and insulin. 3. O-Ethyl O-p-nitrophenyl phenylpropylphosphonate markedly decreased the radioactivity both of the intermediate fractions and of insulin, but had no significant effect on the biosynthesis of the polypeptide. In contrast, puromycin inhibited the incorporation of radioactivity into all the fractions. 4. The polypeptide had an activity of less than 0.2 international unit/mg. in the epididymal-fat-pad bioassay. Treatment with low concentrations of trypsin caused a progressive increase in the formation of an insulin-like material, judged by bioassay and ion-exchange chromatography of the digest. 5. Gel filtration of the polypeptide after oxidative sulphitolysis indicated that it was a single polypeptide chain. 6. The results suggest that the polypeptide is an insulin precursor whose formation is inhibited by puromycin and that the steps involved in the conversion of precursor into product are sensitive to O-ethyl O-p-nitrophenyl phenylpropylphosphonate.

Animals↗
PubMed1968

The sequence of amino acids in insulin isolated from islet tissue of the cod (Gadus callarias).

1. S-Aminoethylcysteinyl derivatives of the A and B chains of cod insulin were prepared from the individual S-sulpho chains. 2. Studies on small peptides derived from the S-aminoethylated peptide chains by treatment with trypsin allowed the amino acid sequences in the region of the cysteinyl residues of the A and B peptide chains to be defined. 3. The six amide groups in cod insulin were located by complete digestion of small peptides from the A and B chains with aminopeptidase followed by amino acid analyses. 4. The results, together with previous studies on the oxidized A and B chains, define the sequences of the 51 amino acids that constitute cod insulin.

Amino Acid Sequence↗
PubMedDate not supplied

Structural and functional studies on C4b-binding protein, a regulatory component of the human complement system.

The binding and cofactor activities of C4b-binding protein were examined before and after limited proteolysis by pepsin, trypsin and chymotrypsin. The major fragments generated were characterized by amino acid sequencing, thus establishing the precise points of limited proteolysis. These studies allow a tentative assignment of the cofactor activity site to the residues 177-322 of the 549 amino acid long chain of C4b-binding protein but indicated that residues in the region 332-395 are important in the binding activity.

Amino Acid Sequence↗
PubMedDate not supplied

Localization of the properdin factor complement locus Pfc to band A3 on the mouse X chromosome.

The locus for properdin (properdin factor complement, Pfc), a plasma glycoprotein, has been mapped to band A3 of the mouse X chromosome by in situ hybridization to metaphase spreads containing an X;2 Robertsonian translocation. The X-linkage of the locus has also been confirmed by analysis of Mus musculus x Mus spretus interspecific crosses. The XA3 localization for Pfc places it in the chromosomal segment conserved between man and mouse which is known to contain at least six other homologous loci (Cybb, Otc, Syn-1 Maoa, Araf, Timp).

Animals↗