Studies of posttranslational modifications in spiny dogfish myelin basic protein

The objective of this investigation was to determine whether nonmammalian myelin basic protein contained charge isomers resulting from extensive posttranslational modifications as seen in mammalian MBP. Four charge isomer components from dogfish MBP have been isolated. These forms arise by phosphorylation and deamidation modifications. Components C1, C2 and C3 have been characterized. We are currently characterizing component C8. Dogfish MBP is less cationic than mammalian MBP and has about 50% lower mobility on a basic pH gel electrophoresis relative to human and to bovine MBP. The mammalian component C1, which is unmodified, is modified in the dogfish by phosphorylation. The reduced electrophoretic mobility is largely attributable to the charge reduction resulting from phosphorylation in serine 72, 83, and 120 or 121 in C1, and C3. In component C2, two or three phosphate groups were distributed among residues 134, 138 and 139. It was found that dogfish amino acid residue 30 was a lysine residue and not a glutamate residue as reported in the literature.     

The P2 protein of bovine root myelin: partial chemical characterization.

The P2 protein of bovine root myelin has chemical characteristics which differentiate it from other myelin basic proteins. The tryptic peptide map of the bovine P2 protein is distinctly different from the map of either the rabbit PI protein or the bovine CNS myelin basic protein. The tryptic peptides of the P2 protein show no overlap in either map positions or amino acid content with the peptides of the CNS myelin basic protein. Analysis of the individual peptides in the P2 map accounted for all of the amino acids present in the analysis of the whole protein. The P2 protein has a blocked NH₂-terminus, lysine at its COOH-terminus and no hexosamine. CD studies revealed that the P2 protein has a very stable β-structure in aqueous solution at neutral or basic pH and retains much of this structure in acid and in 8 M urea. It is suggested that these structural properties are relevant to the dual role of the P2 protein as a membrane constituent and as an antigen.     

The chemical composition of bovine vitreous-humour collagen fibres.

The insoluble protein fraction was prepared from the central and posterior peripheral fraction of bovine vitreous humour. The collagen present in this fraction was solubilized by pepsin and fractionated by gel chromatography. Analysis of the solubilized collagen fractions showed that the alpha-chain component had an amino acid composition and yielded a series of CNBr-cleavage peptides that showed it was very similar to type II collagen obtained from articular cartilage. Bovine vitreous-humour collagen alpha-chains differed, however, from those of cartilage collagen in that they had a lower alanine content and differed in their susceptibility to cleavage by CNBr. Satisfactory cleavage was obtained after two CNBr treatments involving reduction and alkylation. In addition, significant quantities of other peptides constituents were present in the vitreous-humour collagen fractions, and the galactose and glucose content of the alpha-chain fraction was more than double that of the same fraction obtained from articular cartilage. Although the origin of the additional peptide constituents in the vitreous-humour collagen preparations is not known, the results obtained indicate that they are probably not derived from a distinct type of alpha-chain component but may be terminal peptides covalently linked to the alpha 1 type-II helical portions of the collagen. The differences in the chemical composition of the vitreous-humour collagen indicate that vitreous-humour fibres are composed of a special type-II collagen.     

The chemical composition of wool. XV. The cell membrane couplex.

The cell membrane complex of wool has been examined by electron microscopy of stained cross sections after immersion of the wool in formic acid. The cell membrane complex of the cortex is considerably modified by the treatment, but that of the cuticle appears unchanged. Resistant membranes from cuticle cells, cortical cells and wool have been prepared by treatment with performic acid-ammonia. Amino acid analyses show that the resistant membranes from the cuticle contain citrulline but those from cortical cells do not. It is concluded that the cell membrane complex of the cuticle differs from that of the cortex. Because of the high lysine content of the resistant membranes, their resistance to chemical attack, the hydrophobicity of epicuticle and the observation of a small amount of epsilon-(gamma-glutamyl)lysine, it is postulated that the resistant membranes may contain an appreciable amount of epsilon-(gamma-glutamyl)lysine cross links.     

Tamm–Horsfall urinary glycoprotein. The chemical composition

1. A revised amino acid and carbohydrate composition of human Tamm-Horsfall glycoprotein is presented. 2. No significant differences were obtained in the amino acid composition of Tamm-Horsfall glycoprotein isolated from patients with cystic fibrosis. 3. The glycoprotein was shown to possess a high half-cystine content of 1 per 11-12 amino acid residues, which has been confirmed by performic acid oxidation and S-alkylation with iodoacetate and iodoacetamide. No thiol groups were detected in the glycoprotein. 4. Treatment of the glycoprotein with 0.5m-sodium hydroxide at 4 degrees C for 2 days did not release heterosaccharide material, which suggests that the predominant carbohydrate-protein linkages present are not of the O-glycosidic type. 5. No N-terminal amino acid was detected in the glycoprotein.     

The chemical composition of Microbiota decussata

From the leaves of Microbiota decussata (Cupressaceae) biflavones: cupressuflavone, amentoflavone and 7-O-methylamentoflavone were isolated and identified. The amount of cupressuflavone in Microbiota decussata and xCupressocyparis leylandii (Leyland cypress) (Cupressaceae) was determined by HPLC (1.82% and 0.83%, respectively). The chemical composition of essential oils from bark and leaves of Microbiota decussata was established by GC-MS (GC-FID) analysis. As a major component thujopsene (39.2% and 45.9%, respectively) was identified. Wiridiflorol (3.0%) and tau-muurolol (0.3%) were present only in leaves but globulol (1.5%) exclusively in bark. The content of essential oils in M. decussata was high--5.4% in bark and 12.6% in leaves. The essential oils from M. decussata and xC. leylandii were bioassayed towards different fungi of the genus Fusarium. Leyland cypress essential oil at 2% concentration fully inhibited the growth of all fungi.     

The composition of the myelin proteins of the peripheral nervous system

Abstract— A method for the isolation of peripheral nerve myelin is described. Peripheral nerve myelin differs from centrum ovale myelin in its amino acid composition, in that it contains a greater proportion of protein that is digestible with trypsin and pepsin, and in the insolubility of its proteins in chloroform–methanol.     

The composition of the myelin proteins of the central nervous system

Abstract— The amino acid composition of human, monkey and bovine centrum ovale myelin, of bovine optic nerve myelin, and of bovine spinal cord white matter myelin has been determined. In general, the amino acid patterns of the centrum ovale myelin of these species and the optic nerve myelin are identical. Differences are noted when these are compared to the spinal cord white matter myelin. It is shown that the amino acid composition of myelin cannot be duplicated by any combination of the Folch–Lees proteolipid protein and the basic protein fraction of myelin. It is necessary to postulate the existence of a third protein fraction that is rich in dicarboxylic amino acids.     

The chemical composition of interstellar molecular clouds

Relative abundances for molecules observed by radio astronomical techniques have been determined for several interstellar regions with differing physical properties.