Carbohydrates hormonal control

Hormones have a profound effect on carbohydrate metabolism. Great interest has been aroused by reports of hormonal control of hexokinase activity by specific proteins in animal tissues.99- 100 Hexokinase action is the rate-limiting step in the uptake of D-glucose by muscle. Hexokinase is inhibited in diabetic muscle, but the inhibition can be partially reversed by insulin. A protein fraction from the anterior pituitary gland will inhibit the hexokinase of extracts of brain and muscle, and the effect of this... 

Adipokinetic hormones control metabolism of insects during long-distance flight.359 363 In the migratory locust these hormones consist of a pair of related octapeptides and a decapeptide (Table 30-5). The hormones stimulate triacylglycerol lipase in the insects fat bodies, induce release of carbohydrates from body stores, and affect many other aspects of metabolism.363 Insects also have hormones of the insulin family, proteins consisting of disulfide-linked A and B chains as in insulin. The silkworm Bombyx mori has 38 genes for the insulinlike bombyxins, which are synthesized in the brain.364... 

The first section deals with protein, lipid and carbohydrate metabolism, its hormonal control and the adaptations that occur in birds. The second covers the avian genome, gene expression and avian immunology. Growth and em-bryological development are also discussed. 

Insulin is a hormone manufactured by the beta cells of the pancreas. It is the principal hormone required for the proper use of glucose (carbohydrate) by the body. Insulin also controls the storage and utilization of amino acids and fatty acids. Insulin lowers blood glucose levels by inhibiting glucose production by the liver. 

In addition to fiber and carbohydrate content, protein intake from legumes may have weight-loss benefits for obese individuals just because proteins enhance post-meal satiety (Rolls, 1995). However, a possible specific role for phytoestrogens in obesity has been postulated through the modulation of the satiety response, a neuroendocrine mechanism controlled by leptin (a hormone secreted by adipose tissue and already known to be regulated by... 

There are many examples of phosphorylation/dephosphorylation control of enzymes found in carbohydrate, fat and amino acid metabolism and most are ultimately under the control of a hormone induced second messenger usually, cytosolic cyclic AMP (cAMP). PDH is one of the relatively few mitochondrial enzymes to show covalent modification control, but PDH kinase and PDH phosphatase are controlled primarily by allosteric effects of NADH, acetyl-CoA and calcium ions rather than cAMP (see Table 6.6). 

In all organisms, carbohydrate metabolism is subject to complex regulatory mechanisms involving hormones, metabolites, and coenzymes. The scheme shown here (still a simplified one) applies to the liver, which has central functions in carbohydrate metabolism (see p. 306). Some of the control mechanisms shown here are not effective in other tissues. 

Nucleic acids, proteins, some carbohydrates, and hormones are informational molecules. They carry directions for the control of biological processes. With the exception of hormones, these are macromolecules. In all these interactions, secondary forces such as hydrogen bonding and van der Waals forces, ionic bonds, and hydrophobic or hydrophilic characteristics play critical roles. Molecular recognition is the term used to describe the ability of molecules to recognize and interact bond—specifically with other molecules. This molecular recognition is based on a combination of the interactions just cited and on structure. 

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