Biosynthesis of carbohydrates by enzymes from aspergillus flavus, liver and green gram

Abstract

A number of solvents and solvent combinations, and the use of multiple development techniques for efficient separation on filter paper, are described. A series of colour reagents useful for the identification of specific groups of sugars are given. A simple paper chromatographic method for the colorimetric estimation of reducing sugars with the use of triphenyltetrazolium chloride as a colour reagent is also described. Applications of these procedures in the analysis of natural materials prove their efficacy.

Chapter IV deals with the occurrence of soluble oligosaccharides in leguminous plants. The oligosaccharides present in green gram (Phaseolus radiatus) have been isolated by chromatography on charcoal and cellulose columns and characterized by employing physical, chemical, and enzymic methods of analysis. A study of the changes during germination and the role of the various enzymes has also been undertaken.

In recent years, a concept has developed that the action of disaccharide?hydrolysing enzymes is accompanied by some degree of enzymic transfer of sugar residues. This is interpreted as a result of transfer of sugar residues from the disaccharide, acting as donor, to the various sugars present in the reaction which act as acceptors. Thus, during the hydrolytic digestion of purified invertase on sucrose, it was observed that a number of oligosaccharides were formed in the course of the reaction. Similar reactions have now been observed with other disaccharide?hydrolysing enzymes.

The author has studied some of the transferring enzymes present in the typical extracts of Aspergillus flavus, germinating green gram (Phaseolus radiatus), takadiastase, and rat liver. The results are recorded in Chapters X to V of Part II of the thesis.

Chapter I gives a brief introduction to carbohydrate?transferring enzymes and a study of the changes brought about by the enzymic systems of Aspergillus flavus adapted to various disaccharide substrates. The linear dextrins formed have been isolated in pure form and characterized.

Results of the study of the products formed are presented.

Chapter II describes the isolation of the oligosaccharides formed from the disaccharides lactose, cellobiose, and sucrose by the action of enzymic extracts of Aspergillus flavus, and their characterization by physical, chemical, and enzymic methods.

Chapter III deals with the kinetics of the action of the various partially purified transglycosidases.

Chapter IV describes the formation of isomaltose (arising from maltose) by the purified enzyme systems of rat liver.

Chapter V presents enzymic hydrolysis of starch by fungal amylases using the circular paper chromatographic technique.

It is well known that plants are capable of synthesizing sucrose in the dark from supplied monosaccharides.

Chapter VI reports the results obtained by incubating sugars, sugar phosphates, and other substances with green gram plants in relation to sucrose synthesis.