STUDIES ON SOME OF THE ENZYMES OF CARBOHYDRATE METABOLISM AND THE CHEMICAL COMPOSITION OF HEN TIBIA

Abstract

Periosteum, cartilage, epiphyseal head, cortical shaft, and marrow of the tibia of White Leghorn hen were studied for chemical composition with regard to calcium, phosphorus, nitrogen, hexosanaine, and moisture, and the cartilage, epiphyseal head, and cortical shaft were also analyzed for citric acid content. In cortical shaft, cartilage, and epiphyseal head the calcium, phosphorus, and hexosamine contents were higher and the nitrogen was lower than in periosteum and marrow. The former parts also showed a greater degree of calcification as judged by Ca:P and Ca:N ratios. Studies were made on the distribution of key enzymes of glycolysis, of the tricarboxylic acid cycle, the hexose monophosphate shunt, and of certain other enzymes in those parts of the tibia that were studied. These enzymes were α-glucan phosphorylase, lactate dehydrogenase, citrate synthase, aconitate hydratase, isocitrate dehydrogenase (NADP), glucose-6-phosphate dehydrogenase, fumarate hydratase, glutamine synthetase, hexosamine synthetase, and L-aspartate: 2-oxogiutarate aminotransferase.The activity of lactate dehydrogenase was found to be much higher than that of the other enzymes in all the regions studied, which strengthens the hypothesis of a greater degree of glycolysis in bone.The activities of aconitate hydratase, isocitrate dehydrogenase (NADP), fumarate hydratase, and lactate dehydrogenase were lower in cortical shaft than in other regions of the bone. Glutamine synthetase was found in marrow but not in the other parts studied. In general, the marrow was found to be enzymically more active than the other regions.