Portland Press Ltd.
Công bố khoa học tiêu biểu
Sắp xếp:
Studies of the bulbo-urethral (Cowper's)-gland mucin and seminal gel of the boar 1. Moving-boundary electrophoresis of the mucin from the Cowper's gland of the boar revealed a sharp single peak at pH values from 1.1 to 9.0 and an isoelectric point of 1.1. 2. Neuraminidase treatment of the mucin, which removed at least 96% of the sialic acid groups, decreased the electrophoretic mobility at pH4 from −7.4×10−5 (for the mucin) to −0.64×10−5cm2V−1s−1. 3. Ultracentrifugal sedimentation values of s20,w showed a marked dependence on concentration. A hyperfine peak, similar to that given by ovine submaxillary secretion, persisted throughout the run at higher concentrations. Ultracentrifugal studies further showed a very low value for the diffusion coefficient (D20,w −1.57×10−8cm2/s). 4. Calculation of the approximate molecular weight from comparable s20,w and D20,w values gave a provisional value of 6.5×106. 5. Two proteins present in the boar vesicular secretion known as protein A and protein H (the haemagglutinating protein) were shown to promote the swelling of the mucin to form the characteristic rigid elastic gel of boar semen. It is suggested that protein A molecules particularly (mol.wt. 2.8×104) cross-link with the long molecules of the mucin to form the seminal gel.
Portland Press Ltd. - Tập 117 Số 5 - Trang 981-988 - 1970
<i>N</i>-Acetyl-β-glucosaminidases in human spleen 1. The N-acetyl-β-glucosaminidase of human spleen has been separated by gel electrophoresis into two components, an acidic form A and a basic form B. 2. The two forms are readily separated on DEAE-cellulose and have been concentrated 50-fold and sevenfold respectively. 3. They show similar Km values towards 4-methylumbelliferyl N-acetyl-β-d-glucosaminide, and have the same pH optima when compared in citrate, phosphate or acetate buffers. They are inhibited to a similar extent by acetate, heparin, N-acetylgalactosaminolactone, N-acetyl-β-d-galactosamine and N-acetyl-β-d-glucosamine. Specificity for C-4 orientation is not absolute and p-nitrophenyl β-galactosaminide is also hydrolysed but at a rate only 11·6% of that for the corresponding glucosaminide. 4. N-Acetyl-β-glucosaminidase B is stable over a wider pH range than is N-acetyl-β-glucosaminidase A, and is less easily denatured by heat. 5. Tissue fractionation indicates that both the A and B forms are present in the lysosomal fraction, whereas the supernatant contains the A form only. 6. Evidence is presented to indicate that the A form contains a number of sialic acid residues.
Portland Press Ltd. - Tập 107 Số 3 - Trang 321-327 - 1968
Mammalian glycosidases. Distribution in the body
Portland Press Ltd. - Tập 71 Số 2 - Trang 318-325 - 1959
Molecular weight of human placental lactogen investigated by gel filtration
Portland Press Ltd. - Tập 111 Số 5 - Trang 799-800 - 1969
The fatty acid composition of human depot fat
Portland Press Ltd. - Tập 78 Số 3 - Trang 541-550 - 1961
Xanthine oxidase inactivation by reagents that modify thiol groups 1. The presence of xanthine was required for the inhibition of bovine milk xanthine oxidase by o-iodosobenzoate, iodoacetamide, hydrogen peroxide or p-chloromercuribenzoate. 2. Inactivation by p-chloromercuribenzoate was very rapid, was reversed by cysteine and was less in the presence of FAD. Lineweaver–Burk plots showed that the inactivation by p-chloromercuribenzoate was competitive with substrate. 3. Inactivation by o-iodosobenzoate, iodoacetamide or hydrogen peroxide could not be reversed by cysteine or xanthine. However, the presence of xanthine during the incubation with inhibitor protected the enzyme against o-iodosobenzoate but not against iodoacetamide or hydrogen peroxide. 4. p-Chloromercuribenzoate protected the enzyme against inactivation by hydrogen peroxide.
Portland Press Ltd. - Tập 105 Số 2 - Trang 585-589 - 1967
The control of synthesis of bacterial cell walls. Interaction in the synthesis of nucleotide precursors Phosphoenolpyruvate–UDP-N-acetylglucosamine enolpyruvyltransferase, UDP-N-acetylglucosamine pyrophosphorylase and CDP-glycerol pyrophosphorylase activities were demonstrated in soluble extracts from Bacillus licheniformis A.T.C.C. 9945. The effect of various nucleotides, sugar nucleotides and sugar phosphates on the nucleotide pyrophosphorylases was investigated. UDP-N-acetylglucosamine pyrophosphorylase was inhibited by UDP-MurAc-pentapeptide (UDP-N-acetylmuramyl-l-alanyl-d-glutamyl- meso-diaminopimelyl-d-alanyl -d-alanine) and CDP-glycerol. CDP-glycerol pyrophosphorylase was inhibited by UDP-MurAc-pentapeptide and stimulated by UDP-N-acetylglucosamine. Interaction between a precursor of one cell-wall polymer and an enzyme involved in the synthesis of a precursor of a second polymer has therefore been demonstrated. The possible role of such interaction in the control of bacterial cell-wall synthesis is discussed. Of the other compounds investigated mono- and di-nucleotides were shown to be inhibitory, indicating that nucleotide pyrophosphorylase activities may be influenced by the energy charge of the cell.
Portland Press Ltd. - Tập 136 Số 4 - Trang 871-876 - 1973
Effect of growth hormone on fibrinogen synthesis A method described by McFarlane (1963a) for the measurement of the absolute rate of synthesis of liver-made plasma proteins was used to show that, within a few hours of giving bovine growth hormone to rats, fibrinogen synthesis increased significantly without a change in albumin synthesis.
Portland Press Ltd. - Tập 119 Số 2 - Trang 243-249 - 1970
The effect of hypophysectomy and growth hormone replacement on albumin synthesis and catabolism in the rat Albumin synthesis and catabolism were respectively measured by McFarlane's (1963) sodium [14C]carbonate method and I-labelled albumin in hypophysectomized rats, both untreated and treated with growth hormone. Hypophysectomy resulted in a decrease in both albumin synthesis and catabolic rates. These changes as shown by pair-feeding experiments could not be ascribed to decreased food intake alone. Growth hormone was shown to partially restore both albumin synthesis and catabolic rates. It is proposed that growth hormone stimulates albumin synthesis and that its effect on albumin catabolism is secondary to changes in the mass of the intravascular albumin pool.
Portland Press Ltd. - Tập 124 Số 3 - Trang 529-535 - 1971
Tổng số: 115
- 1
- 2
- 3
- 4
- 5
- 6
- 12