Phenylalanine, oxidation

Substantial improvement (about 50%) of lemon oil encapsulation efficiency was attained for the covalently-linked phenylalanine-Oxidized starch wall material over the Oxidized starch control. In fact, this particular glycoamine resulted in lemon oil retentions following drying in the mini-spray dryer which surpassed both the Control and lipophilic starches (See Table IV). Dry blending phenylalanine with the Oxidized starch base exhibited the benefits associated with covalently linked glycoamine production via lemon oil vapor phase flux analysis. 

The biopterin product is recycled by elimination of water, reduction using NADPH as the reagent, and reaction with molecular oxygen. The other product, the phenylalanine oxide, rearranges with a hydride shift followed by the loss of a proton to give tyrosine. 

Sow reproductive performance was similar to commercial standards (litter size 14.0 2.6 litter birth weight 21.3 4.3 kg). Figure 1 shows the response of sows to increasing dietary THR based on L[l- C]phenylalanine oxidation. The THR requirement in early pregnancy was 5.0 1.0 g/d (R =0.71) and in late pregnancy 12.3 2.3 g/d (R =0.58) based on indicator amino acid oxidation (Table 1). 

Figure 1. The response of sows to increasing levels of dietary threonine intake based on [l- C] phenylalanine oxidation (A early gestation, B late gestation).

Acetoxy-l,7-octadiene (40) is converted into l,7-octadien-3-one (124) by hydrolysis and oxidation. The most useful application of this enone 124 is bisannulation to form two fused six-membered ketonesfl 13], The Michael addition of 2-methyl-1,3-cyclopentanedione (125) to 124 and asymmetric aldol condensation using (5)-phenylalanine afford the optically active diketone 126. The terminal alkene is oxidi2ed with PdCl2-CuCl2-02 to give the methyl ketone 127 in 77% yield. Finally, reduction of the double bond and aldol condensation produce the important intermediate 128 of steroid synthesis in optically pure form[114]. 

One ammo acid often serves as the biological precursor to another L Phenylala nine is classified as an essential ammo acid whereas its p hydroxy derivative L tyro sine IS not This is because animals can convert L phenylalanine to L tyrosine by hydrox ylation of the aromatic ring An arene oxide (Section 24 7) is an intermediate... 

An entry to. yyrt-2-methoxy-3-hydroxycarboxylic acids is also opened using similar methodology. Thus the norephedrine derived (4/ ,5S)-3-(2-methoxy-l-oxoethyl)-4-methyl-5-phenyl-1,3-oxazolidine-2-one 23105a, as well as the phenylalanine derived (4S)-4-benzyl-3-(2-methoxy-l-oxoethyl)-l,3-oxazolidin-2-one 25105b, can be added to aldehydes via the boron enolates to give, after oxidative workup, the adducts in a stereoselective manner (d.r. 96 4, main product/sum of all others). Subsequent methanolysis affords the methyl esters. 

Very low asymmetric induction (e.e. 0.3-2.5%) was noted when unsymmetrical sulphides were electrochemically oxidized on an anode modified by treatment with (— )camphoric anhydride or (S)-phenylalanine methyl ester299. Much better results were obtained with the poly(L-valine) coated platinum electrodes300. For example, t-butyl phenyl sulphide was converted to the corresponding sulphoxide with e.e. as high as 93%, when electrode coated with polypyrrole and poly(L-valine) was used. 

Phosphorus pentachloride, for conversion of pentaacetylgluconic add to add chloride, 41, 80 for oxidation of cycloheptatriene to tropylium fluoborate, 43, 101 with cyanoacetic acid, 41, 5 Phosphorus tribromide, reaction with 1.5-hexadien-3-ol, 41, 50 Phthalic anhydride, reaction with L-phenylalanine to yield N-phthalyl-L-phenylalanine, 40, 82 Phthalic monoperacid, 42, 77 N-Phthalyl-i.-alanine, 40, 84 N-Phthalyl-/3-alanine, 40, 84 N-Phthalylglycine, 40, 84 N-Phthalyl-l-/5-phenylalanine, 40, 82... 

The Jing group investigated their poly(L-lysine)-6-poly(L-phenylalanine) vesicles for the development of synthetic blood, since PEG-lipid vesicles were previously used to encapsulate hemoglobin to protect it from oxidation and to increase circulation time. They extended this concept and demonstrated that functional hemoglobin could be encapsulated into their vesicles. The same polypeptide material was also used to complex DNA, which caused the vesicles to lose their... 

Chen D, PA Frey (1998) Phenylalanine hydroxylase from Chromobacterium violaceum. Uncoupled oxidation of tetrahydropterin and the role of iron in hydroxylation. J Biol Chem 273 25594-25601. 

The anaerobic metabolism of L-phenylalanine by Thauera aromatica under denitrifying conditions involves several steps that result in the formation of benzoyl-CoA (a) conversion to the CoA-ester by a ligase, (b) transamination to phenylacetyl-CoA, (c) a-oxidation to phenylglyoxalate, and (d) decarboxylation to benzoyl-CoA (Schneider et al. 1997). 

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