Hormones enzyme action

A good example of substrate specificity in enzyme action is the metabolism of juvenile hormone (JH) analogs by insects. In a series of experiments summarized in Table 9.7 to 9.10, the activity of esterases and microsomal monooxygenases from three dipterans against 12... 

A pro-drug is a substance that has no special biological activity per se but can be converted into an active drug by enzymic action in the body. Thus, all the initial proteins formed by ribosomal synthesis that contain a peptide hormone structure locked within their amino-acid sequence are analogous to pro-drugs. The hormones are released by the action of proteolytic enzymes. Usually, however, the term prodrug is restricted to artificially synthesised molecules that are acted upon by the... 

Estrogens are a class of female sex hormones that include estrone and estradiol. As shown in Figure 19.24, estrogens are derived from the androgens (male sex hormones) by action of the enzyme aromatase. 

It has been widely accepted that the mode of action of certain hormones is a direct interaction with enzymes. In the case of thyroid hormones, however, inconsistencies in the data are so fundamental that some investigators now seriously doubt whether a hormone-enzyme interaction does, indeed, represent their mechanism of action. J or hormonal activity to be exerted on enzymes, it has been assumed that the effect must be mediated through acceleration or inhibition of a pacemaker. The variety of enzymes affected by the in vim administration of thyroxine makes it most unlikely that altered activity of an appropriate pacemaker will, in fact, be demonstrated. Further, it has already been shown that many of the observed changes in enzyme activity are secondary to effects on vitamin metabolism, metal ions, or membranes. In addition, all the in vitro effects on enzymes have required for their demonstration concentrations of thyroxine... 

Effect of pH on AA, 6 Enzyme action, 283 Enzyme activation by AA, 295-302 Enzyme inhibition by AA, 295-302 Enzyme mechanism, 284 Enzyme mechanism and AA, 284, 285 Enzyme mobilizing hormone (AA), 107 EPR, 129-131... 

At present there are no data which could allow differentiation between the hormone-signal thesis and the hormone-enzyme view, nor is the one apparently more susceptible to experimental investigation than the other. The fundamental question of energy transfer in muscle contraction remains frustratingly elusive, despite the high order of understanding of the interactions of the individual components involved to produce action... 

Factors which alter /3-glucuronidase in tissue have been described as hormones, vitamins, age, and othere. The studies on renotrophic actiort of /3-gIucuronidase to androgen have produced one of the clearest models of hormone-enzyme reaction. This research clarified one facet of the triangular relationship which unites the enzyme, membi-ane, and hormone action. 

CCK is found in the digestive tract and the central and peripheral nervous systems. In the brain, CCK coexists with DA. In the peripheral nervous system, the two principal physiological actions of CCK are stimulation of gaU. bladder contraction and pancreatic enzyme secretion. CCK also stimulates glucose and amino acid transport, protein and DNA synthesis, and pancreatic hormone secretion. In the CNS, CCK induces hypothermia, analgesia, hyperglycemia, stimulation of pituitary hormone release, and a decrease in exploratory behavior. The CCK family of neuropeptides has been impHcated in anxiety and panic disorders, psychoses, satiety, and gastric acid and pancreatic enzyme secretions. 

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