The Chemical Nature of Hormones

The chemical nature of hormones is extremely variable. Hormones can be  

Preparation of the uterus for implantation of the embryo, maintenance of early pregnancy 

Preparation of the uterus to receive the blastocyst, control of uterine constraction, 

Differentiation and growth of the male reproductive tract, stimulation of male secondary sex characteristics, sceletal muscle growth 

Metabolism of carbohydrates, lipids and proteins, anti-inflammatory, immunsuppressive 

Metabolism of carbohydrates, lipids and proteins, anti-inflammatory, iimmunsuppressive induction of Tyr-aminotransferase and of T rp-cyclooxygenase 

---

The chemical natures of hormones play a predictably important role in their roles in cell signaling. Steroid hormones, for example, can enter the cell directly through the plasma membrane or can bind to plasma membrane receptors. Nonsteroid hormones enter the cell exclusively as a result of binding to plasma membrane receptors (Figure 24.8). 

The serum in the medium is not only expensive but also can be the source of virus or mycoplasma contamination. Since the chemical nature of serum is not well defined, its contents may vary batch after batch, which can affect the result of culture. The presence of many different proteins in serum can also complicate the downstream separation processes. For these reasons, many attempts have been made to formulate serum-free media. These formulations contain purified hormones and growth factors which can substitute for serum supplements (Butler, p.ll, 1987). 

The chemical nature of the hormone seems to have varying effect on copper metabolism. Gonadal hormones, for example, increase ceruloplasmin by a mechanism of de novo synthesis of the protein independent of copper concentration in the liver, whereas hormones of the thyroid, adrenal, and pituitary influence copper metabolism in an indirect manner by decreasing its biliary excretion 144),... 

One of the major aims of this review has been to examine the current status of immunological assays used to measure the pituitary gonadotropic hormones. Since all immunoassays basically depend on the interaction of an antigen of unique identity (in this case FSH or LH) and its specific antibody, it was necessary also to discuss the chemical nature of the various preparations of FSH and LH which are currently available and to consider the concept of antibody specificity as it applies in this field. 

Biofunctional natural products with low molecular weights are classified as shown in Table 1.1. Chemical studies on vitamins, hormones and antibiotics started in the first half of the 20th century, while those on semiochemicals began in the middle of the 20th century. This book treats the chemical synthesis of hormones, pheromones and other bioregulators such as allelochemicals. 

Other pituitary hormones. It is hoped that the amino acid sequence of these peptides will soon be determined and thus that the chemical nature of the corticotrophin-releasing factor(s) will finally be elucidated. Of course, this type of method may also be of considerable potential value in the identification of other hypothalamic hormones. 

Phosphorylation of the hydroxyl group of a serine, threonine or tyrosine residue in the enzyme (Figure 3-3), thus altering the chemical nature of its catalytic site. As discussed in section 10.3, phosphorylation of the enzyme is also important in regulating metabolic pathways, especially in response to hormone action. 

The Biosynthesis begins with tyrosine. The pathway of reactions shown here also provides information about the chemical nature of the hormones. 

It has been proposed that cyclic AMP may be a "second messenger" In hormone action In some tissues.9 The hormone Itself ("first messenger") may react with a portion of the adenyl cyclase molecule which faces the extracellular space thereby Inducing conformational changes in other portions of the molecule (on the inside of the cell membrane). This cotild activate adenyl cyclase and Increase the rate of synthesis of cyclic AMP ("second messenger") which could then produce the response.91 This Is an attractive theory and Is In agreement with existing facts but more Information about the chemical nature of adenyl cyclase will be required before the hypothesis can be accurately evaluated. 

Endocrine gland Principal hormone secretions Chemical nature of the hormone... 

This concludes what I have to say about the steroids. A constantly recurrent theme is the sensitive nature of biological activity to chemical structure. Details of chemical structure determine if and how small molecules such as steroids interact with the large molecules, say the steroid hormone receptors, to effect biological change. Such interactions are notably sensitive to molecular size and shape. 

Outline of pathways for the biosynthesis of major cellular lipids (other than cholesterol) in a mammalian cell. Most of the metabolism of these lipids occurs on membrane surfaces because of the insoluble nature of the substrates and products. These lipids play three major roles (l) they act as a storehouse of chemical energy, as with triacylglycerols (2) they are structural components of membranes (boxed compounds) and (3) they act as regulatory compounds (underlined), either as eicosanoids, which act as local hormones, or as phosphorylated inositols and diacylglycerols, which function as second messengers. 

---