Biomedical subjects
J C Wriston
Publications and source records attributed to J C Wriston.
Comparative biochemistry of the guinea-pig: a partial checklist.
A great deal is known about guinea-pig biochemistry, but the information is scattered and difficult to assemble. The guinea-pig also possesses a number of unusual biochemical features which add to its interest. For these reasons we have compiled a list of biochemical characteristics of the guinea-pig, organized in a series of tables, with brief discussions of some of the entries.
On the distribution of plasma L-asparaginase.
The guinea-pig, Cavia porcellus, is unusual in possessing plasma L-asparaginase, an enzyme with anti-tumor activity, 21 additional species have been examined as to the presence of this enzyme: the results confirm and extend its remarkably limited species distribution.
Chemical modifications of Escherichia coli L-asparaginase and their effect on plasma clearance rate and other properties.
Escherichia coli asparaginase (L-asparagine amidohydrolase, EC 3.5.1.1) has been modified by succinylation, acetylation and the attachment of N,N-dimethyl-1,3-propanediamine and glucuronic acid. The effect of these modifications on plasma clearance rates in mice and on other properties is compared to the effects of modification with lactose and N-acetylneuraminyl lactose studied previously. The t 1/2 values for the acylated enzyme samples (lower pI) were reduced, succinylated asparaginase sharply and the acetylated enzyme less so. The N,N-dimethyl-1,3-propanediamine-modified samples (increased pI) also had lower t 1/2 values, but samples modified with glucuronic acid (reduced pI) showed little change in clearance time. The main conclusion is that the increased t 1/2 value found in the previous work for N-acetylneuraminyl-lactosylated enzyme is not due to the decreased pI value of the modified enzyme, but must be attributed to interference by N-acetylneuraminyl-lactose residues, directly or indirectly, with the mechanism normally used by the mouse to clear itself of injected E. coli asparaginase.
Preparation, properties, and applications of carbohydrate conjugates of proteins and lipids.
As a result of the growing awareness of the involvement of the oligosaccharide moieties of glycoproteins and glycolipids in cell surface recognition and binding phenomena, a wide variety of methods have been developed, many quite recently, for preparing glycoconjugates. The chemical methods used for the attachment of sugars and certain hydrophilic polymers (e.g., polyethylene glycol) are discussed, as are the effects of such modifications on various properties of the protein (immune response, thermal stability and resistance to proteolysis, clearance, and specific binding to cell surface receptors). Enzymatic approaches to glycoconjugate preparation are also considered, and several examples are given of the preparation of model glycolipids, useful in studying cell surface phenomena. In a final section, three areas are considered in which rapid advances seem likely to occur: improved methods for the preparation of glycoconjugates; direct modification of cell surface glycoconjugates; and modification for the purpose of studying location and environment of membrane glycoconjugates.
Influence of incorporated cerebrosides on the interaction of liposomes with HeLa cells.
The presence of synthetic N-palmitoyl dihydrolactocerebroside in preparations of neutral multilamellar liposomes enhances their fusion interaction with cultured HeLa cells some 5-7 fold. The effect appears to be carbohydrate-specific, and is probably not attributable to a change in the physical characteristics of the liposome bilayer due to the presence of the cerebroside.
Glycosylation of Escherichia coli L-asparaginase.
Reductive coupling with sodium cyanoborhydride has been used with lactose and N-acetylneuraminyl lactose to prepare glycosylated Escherichia coli L-asparaginase. A substantial degree of modification can be achieved without significant loss of enzyme activity. The lactosylated enzyme shows increased thermal stability and resistance to proteolytic cleavage and is cleared more rapidly from the plasma of mice, compared to native asparaginase. The effect on clearance varies directly with the degree of lactosylation. Asparaginase modified with N-acetylneuraminyl lactose, in contrast, with approximately 13.6 mol of N-acetylneuraminyl lactose/mol of enzyme, is cleared more slowly, with a t 1/2 that is approximately twice that of the native enzyme.
Purification and properties of L-asparaginase from Serratia marcescens.
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Purification and partial sequencing of cyanogen bromide peptides from L-asparaginase of Escherichia coli B.
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Modification of chymotrypsinogen with 1-aminoglucose.
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Chemical evidence for identical subunits in L-asparaginase from Escherichia coli B.
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Purification and properties of an L-asparaginase from Fusarium tricinctum.
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Purification and properties of Bacillus coagulans L-asparaginase.
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Subunit structure of L-asparaginase from Escherichia coli B.
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Purification and properties of asparaginase from escherichia coli B.
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The isolation of porcine ribonuclease, a glycoprotein, from pancreatic juice.
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Partial purification and antilymphoma activity of Serratia marcescens L-asparaginase.
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