Hydroxamate group

Apparently, the small hydroxamate group also interferes with the inclu-... 

The first example of this type of reaction was provided by Kunitake and coworkers who found that deacylation ofp-nitrophenyl acetate by functional surfactants containing oximate or hydroxamate groups was strongly accelerated by tri-n-octylmethylammonium chloride (Okahata et al., 1977). 

The crystal structure of the catalytic domain of human neutrophil collagenase with bound batimastat (Fig. 7) shows that batimastat coordinates to the catalytic zinc(II) in a bidentate manner via the hydroxyl and carbonyl oxygens of the hydroxamate group (Fig. 29)... 

The hydroxamate group in the copolymer of equation (7) is not particularly reactive, but is activated by the addition of hydrophobic ammonium salts (Shinkai et al., 1977b). 

The catalysis proceeds mainly via acylation at the hydroxamate group followed by relatively slow deacylation catalyzed by intramolecular imidazole (13). Due to the labile nature of the acetyl hydroxamate intermediate, [32] and [33] act as true catalysts. The overall catalytic efficiency exceeds even that of... 

Gruhn and Bender (2P) attached a hydroxamate group (8) to a secondary hydroxyl in an attempt to attain rapid turnover of catalyst in phenyl ester hydrolysis. The catalytic rate of the cycloamylose-hydroxamate adduct was compared to the rates brought about by (9) free in solution. Relative to the... 

On the basis of work on enzyme models of low molecular weight, Kunitake and his associates have prepared a variety of vinyl polymers containing the hydroxamate group. Gruhn and Bender (28, 30) investigated compound... 

Finally, the Lessen rearrangement provides a practical procedure for replacing the hydroxamic group of a hydroxamic acid (12) by an amino group (14) (equation 2). The initial rearrangement product is an isocyanate (13) which readily reacts with nucleophiles, for example with OH and NH functionalities to give amines (14) and ureas (15). 

Since the hydroxamate group —N(OH)—CO is intrinsically unsymmetrical, its coordination characteristics do not change when positioned in the reverse direction —CO—N(OH) (in which the positions of the hydroxamate nitrogen and carbon are interchanged). The relationship between these different structures is referred to as retro-hydroxamate isomers. The retro prefix is generally preserved for structures that are reversed to that of the naturally occurring structure. 

As explained above in Section n, incorporation of chiral amino acids in the linker arms between the template and the hgating hydroxamate groups not only allows one to determine the directionality of the hehcal twist, but also permits one to modify the chelator properties such as buUciness, hydrophobicity and receptor selectivity. 

In contrast to the TREN template, 75 with the NTA template preferred the h-cis configuration . This could be caused either due to the inverse directionality of the hydroxamate group, or, more plausibly, because the tripeptide is connected through the amino end, leading to opposite orientation of the hydrogen-bonding network. ... 

The five enantiomeric geometrical isomers of ferrioxamine B. The oxygen donor atoms of each hydroxamate group have been omitted for clarity. The A optical isomer is shown in each case. 

The first known siderophore, isolated in 1952 by Neilands,22 is ferrichrome (Fig. 16-1), a cyclic hexa-peptide containing hydroxamate groups at the ironbinding centers. Oxygen atoms form the bonds to iron... 

Hydroxamic acids have been the subject of six papers 43 90 94 Earlier the operation of the a-effect in the reaction of p-nitrophcnyl acetate with benzohydroxamates in aqueous MeCN was discussed.43 The conformational behaviour of series of mono- (105) and di-hydroxamic acids (106) in MeOH, DMSO, and chloroform and in the solid state has been examined witii IR and NMR spectroscopy.90 X-ray crystal structure determinations of (105 X = Me, R = Me) and die monohydrate of glutarodihydroxamic acid (106 n = 3, R = H) together widi ab initio MO calculations for several hydrated and non-hydrated acids have been performed. The cis-Z conformation of the hydroxamate groups is preferentially stabilized by H-bonding witii water. 

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