Hormones digestive processes

Figure 6.1 Acids and bases exist in the human body and are necessary for its proper function, including the function of the digestion process. When food is swallowed, it is attacked by stomach acids. The stomach acids need to be neutralized before food can continue down the digestive tract. A hormone called secretin monitors the pH balance in the small intestine and sends chemical signals to other parts of the body, thereby regulating pH balance.

Peptide hormones (aglandular hormones), whose action makes possible the secretory processes necessary for the normal course of the digestive process, are formed in the gastric and intestinal mucosae and in the excretory pancreatic tissue (islets of Langer-hans). 

Hormones—Many of the above changes in metabolism are ultimately due to some hormonal change. Most of the hormones direct the metabolic processes. The storage and release of glucose is hormone mediated. Protein synthesis is hormone mediated, as is the release of fatty acids from fats. The thyroid hormones can, on a long-term basis, raise the metabolic rate 100%. Conversely, undersecretion can cause the metabolic rate to fall 50% below normal. Other hormones control water and minerals, and still others control the digestive processes. 

The events in the digestive process are controlled partly by the nervous system, and partly by hormones liberated by the action of the digestive products on the gastric and intestinal mucosa. 

Candidate protease inhibitor drugs must be relatively specific for the HIV-1 protease. Many other aspartic proteases exist in the human body and are essential to a variety of body functions, including digestion of food and processing of hormones. An ideal drug thus must strongly inhibit the HIV-1 protease, must be delivered effectively to the lymphocytes where the protease must be blocked, and should not adversely affect the activities of the essential human aspartic proteases. 

The control of gut function involves interplay between neurones and peptide hormones. Information from a variety of receptors along the digestive tract is processed by a network of nerves, the enteric nervous system, which also receives input from the brain. 

Many proteins are formed as inactive precursors and become activated by proteolysis. The inactive precursors are termed proenzymes, zymogens or - for hormones like e.g. insulin - prehormones. Processing to the active form occius in a cell- and tissue-specific way and usually requires a specific protease. Activation can also occur intramolecu-larly by autoproteolysis. In most cases, short sequences of the protease substrate serve as a recognition signal for the attack of the processing protease. Of the numerous examples of proteolytic processing of proteases only the digestive proteases will be discussed in more detail. 

Virtually eveiy process in a complex organism is regulated by one or more hormones maintenance of blood pressure, blood volume, and electrolyte balance em-bryogenesis sexual differentiation, development, and reproduction hunger, eating behavior, digestion, and... 

Matrix-assisted laser desorption ionization is another ionization mode used for MS analysis. Enzymatically digested peptides have been studied using a 90-well microchip constmcted in a MALDI plate format (see Figure 7.41). Peptide digestion was initiated in the MALDI interface where the peptide hormone, adreno-corticotropin (ACTH) was mixed with the enzyme carboxypeptidase Y. The mixing process was self-activated in the vacuum conditions. Subsequent TOF MS analysis produced kinetic information of the peptide digestion reaction [820]. 

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