Protein-carbohydrate Complexes Research Articles

THE BIOLOGICAL SIGNIFICANCE OF HYALURONIC ACID AND HYALURONIDASE

This review article (87 references) deals with the biological significance of hyaluronic acid, a mucopolysaccharide acid, and the enzyme hyaluronidase. The author suggests that the relationship between bacterial infection and the hyaluronidase system has perhaps undeservedly been the subject of more investigation than metabolism of the acid or its role in animal physiology and pathology. Topics covered relating to the acid include: occurrence, chemistry, extraction, purification, chemical analysis, instrumental analysis (x-ray diffraction (XRD), viscosity, optical rotation). For hyaluronidase, topics discussed are: occurrence; determination (biological methods, chemical analysis and physicochemical methods); mechanism of hyaluronate degradation; influence of environmental factors on enzyme activity (pH, salts, inhibitors, antisera); bacterial hyaluronidases; substrates. The physiological studies include the functions of ocular fluids, synovial fluid, connective tissues and the skin, which in general must partly depend on the quantity and degree of aggregation of hyaluronic acid. Gels formed by the acid serve partly as the mesodermal cement which holds cells together and also as a protective lubricant and shock-absorber in joints. In some connective tissues, they are part of the viscous barriers which regulate the exchange of metabolites and water.

CARBOHYDRATES OF WHEAT LEAVES

Previous work on respiration and carbohydrate metabolism of wheat leaves on prolonged starvation (3) revealed the presence in these leaves of two different respiratory substrates, which were provisionally called the primary and the secondary substrates. The primary substrate has been found to be responsible for the production of C02 by leaves early in starvation, while its contributions in later stages were little or nothing. On the other hand the secondary substrate, which might or might not be used on the first day, was becoming with the progress of starvation of greater and greater importance, until in later stages either (as in some cases) all the C02 emitted by leaves was derived from it, or (as in others) the major portion. It was shown in the same paper that the primary substrate was represented by sugars extracted from leaves by ethyl alcohol. While nothing definite was said on the nature of the secondary substrate it was suggested that this probably consisted of a variety of substances, some of which are of importance in protoplasmic organization. Deleano (1) and Yemm (5) reported that proteins serve as the respiratory substrate in later stages of starvation in the leaves of grape and of barley. But before attention is definitely focused on proteins as the source of secondary substrate in wheat leaves, it ought to be determined whether or not some other carbohydrates, which might serve in this capacity, are present in leaves in sufficiently large amounts. Newton and Brown (4), for example, reported that wheat leaves in later stages of maturity contain considerable amounts of pentosans. Such carbohydrates, if present, must remain in the leaf residue after alcoholic extraction, and they might exist there in the two following forms: (1) as hemicelluloses, (hydrolyzable by 1 per cent. H2S04) ; (2) as part of a carbohydrate-protein complex, from which carbohydrates could be liberated on digestion of its protein fraction by trypsin. To test these two possibilities, the experiments reported below were performed.

Dissociation of the Specific Protein Precipitate of Antipneumococcus Horse Serum, and a Comparison with a Protein Isolated by Chemical Means from this Immune Serum

Summary and Conclusions Afterheating in 0.85 per cent sodium chloride with or without sodium carbonate (Gay and Chickering method), the relationship of protection to nitrogen was found to be approximately the same in precipitate and supernatant fluid of the pneumococcus carbohydrate-protein complex. It has been found possible to dissociate the specific precipitate, that is, separate the soluble specific substance from the protein by means of calcium or strontium phosphate. The protein thus separated is water-insoluble and salt soluble. In the material studied, it protects mice against one million lethal doses of virulent pneumococci, when the protein content is, in case of Type I, 0.0004 mgm. nitrogen per cubic centimeter, and with Type II 0.004 mgm. per cubic centimeter. The protein isolated by dissociation and that isolated by a zinc method are approximately alike in protective titer; both are water-insoluble, but readily soluble in neutral salts, and both alike react in similar fashion in all chemical analyses carried out. The nitrogen percentage by weight of the protein obtained by dissociation was with Type I, 14.9 per cent, and with Type II, 15.2 per cent. Three preparations by the zinc method gave respectively 15.7, 15.3 and 15.5 per cent nitrogen.