AOAs

The two main producers of xanthates ia the United States, ie, American Cyanamid and Dow, shut down their plants ia the 1970s. American Cyanamid transferred its production to Canada, and siace thea has shut dowa that plant. Xanthates ia solutioa are available ia some areas of the United States and Canada and are transported locally by tmck. The U.S. consumption of xanthates for froth flotation was ca 1,812 t/yr ia 1985 (85). la the previously aoa-Soviet bloc the 1995 xanthate usage was estimated at 30,000 metric tons, and ia China and Russia at 25,000 metric tons, for a worldwide total of 55,000 metric tons. The estimated current number of xanthate plants ia the world is 14—16, with oae ia the United States and one ia Canada. 

Antioxidant agent Also called aging retardants. AOAs are of major importance to the plastic industry because they extend the plastic s (that are effected by oxygen) useful temperature range and service life during processing and/or product use. The variety of AOAs available and their specific uses are extensive. 

AOPP and AOA inhibit transaminase enzymes (39, 44) and other pyridoxylphosphate-dependent enzymes, presumably by interference with the carbonyl group of pyridoxyl phosphate (45). They apparently inhibit PAL by interaction with the carbonyl-like group involved in catalysis by PAL (36). AOA is not an effective PAL inhibitor for in vivo studies because of its lack of specificity that results in a relatively high degree of phytotoxicity (e.g. 

It has been patented as a herbicide (46), and the herbicide benzadox (Figure 2, V) is apparently metabolized by plants to AOA, its active in vivo component (47). 

The high toxicity of AOA is due to its very high efficiency as a transaminase inhibitor (K =0.45 pM) as compared to its efficacy as a PAL inhibitor (K. = 120 pM) (48), making it impossible to effectively inhibit PAL iti vivo without also greatly inhibiting amino acid metabolism. Other pyridoxyl phosphate-requiring enzymes, such as ACC synthase (an enzyme involved in ethylene production) (49), are also more sensitive to AOA than to AOPP. 

Also, a good correlation between Mw (light scattering) and intrinsic viscosity is observed for [Ph(Me)PN]n over the molecular weight range of the samples studied. Thus, the Mark-Houwink relationship, [rj] = K(AOa, yields values of K = 1.44x1 o 4 (with [rj] in dL/g) and a = 0.66. These data again indicate a well solvated, extended-chain structure of the polymer in THF. 

American Obesity Association. AOA Fact Sheets, Consumer Protection Weight Management Products Services. Available online at http //www.obesity.org/ subs/fastfacts/Obesity Consumer Protectshtml. 

If the interaction between A and B occurs through the ith atom of A and the Mh atom of B, then the most favorable situation that arises from the minimization of AOa and AOb leads to, vA, =, vB/,. Hence, the interaction between A and B is favored when it takes place between those atoms whose softnesses are approximately equal. This is essentially the local HSAB principle. 

Tiburzy (22,31) obtained similar results by application of the PAL inhibitor aminooxyacetic acid (AOA). However, AOA does not specifically inhibit PAL (99), and PAL is not only involved in lignin biosynthesis (100). Thus, AOA and the related inhibitor aminooxyphenyl propionic acid (AOPP) (101,102) inhibit the biosynthesis of lignin (103,104), anthocyanins (105), other flavonoids (106), and conjugates of cinnamic acids (107) via PAL, as well as ethylene (108-110) via a pyridoxal phosphate dependent enzyme (110,111). In view of the possible function of phenolic compounds as phytoalexins (21,112,113) and the well documented role of ethylene in some resistance reactions (114-116), the above cited experiments with AOA (22,... 

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