Fruit hormone synthesis

Ethylene not only hastens the ripening of fruit but also tends to promote senescence in all parts of plants. Its signaling mechanisms are the best-known for any plant hormone.368 369 Tire synthesis and action of ethylene are discussed in Chapter 24, Section D,4. Ethylene is metabolized slowly in plants by oxidation to ethylene oxide. The latter is hydrolyzed to form ethylene glycol, which is metabolized further to C02 (Eq. 30-3). 

Synthesis of ethylene, a gaseous plant hormone involved in fruit ripening and flower senescence. 

We noted earlier in this chapter (Section II.C.3) the pyridoxal-phosphate-linked enzymatic route of synthesis of ACPC (9) from the a-aminobutyryl moiety of S-adenosylmethionine (99). ACPC (9) undergoes further metabolic processing by two distinct fragmentation routes, to a-ketobutyrate (138) and ammonia (equation 21) in bacteria and yeast or to ethylene (139) in fruit and other plant tissues (equation 22) where ethylene (139) is a potent hormone for fruit-ripening or wound-healing The bacterial enzyme, ACPC deaminase is much better characterized and is taken up first. 

Microbes use enzymes as catalysts to obtain the desired or beneficial reaction and typically under mild conditions. The brewing of beer and fermentation of fruit and vegetable mass high in starches to produce consumable ethanol are the oldest and most familiar examples of using microbial action to achieve a desired end. But now much more has been demonstrated, from the production of essential human hormones to the synthesis of specialty chemicals. 

The methyl ester of jasmonic acid (methyl 3-oxo-2-(2 -pentenyl)-cyclopentaneacetate) is also known as both an active plant hormone and an important fragrance and flavor component with sweet-floral and jasmine-like aroma notes (13). Methyl jasmonate induces plant systems to provide defense from microbial infection, and is a secondary synthesis product of plants. Methyl jasmonate was also isolated from the Oriental fruit moth, Grapholitha molesta as a part of the male sex hormone (7,75). The authors demonstrated that the volatile form of jasmonic acid, methyl jasmonate, is a major signal molecule for inter- and intra species communications. Methyl jasmonate is expected to have... 

Ethene is the hydrocarbon commercially produced in the greatest quantity in the United States. It is used in the synthesis of many plastics and commercially important alcohols. Ethene is also an important plant hormone. Induction of flowering and the ripening of fruit, as shown in Figure 2.10, are effects of ethene hormone action that can be manipulated by commercial growers. 

The manifold biological activities displayed by ACTH peptides - activities that Include hormonal as well as extra-adrenal effects - offer the peptide chemist a fruitful field In which to study the relationship between structure and function. Earlier work undertaken In the laboratories of LI, Hofmann, Bolssonnas, and Schwyzer was directed towards the synthesis of active ACTH fragments. These efforts culminated In the successful synthesis of hog-type corticotropin by Schwyzer and Sleber (l) and, more recently, of human corticotropin by a Hungarian group (2). In recent years, however, attention has shifted towards the preparation of modified ACTH peptides, and It has been demonstrated that the natural amino acid sequence of corticotropin peptides can be altered considerably with retention of or even an... 

Gibberellic acid A class of plant growth substances or phytohormones. It is chemically classified as a diterpenoid. The hormone influences seed germination, amylase synthesis, break of dormancy, and fruit and leaf growth. It is the most important hormone for germination. 

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