19379-33-0Relevant articles and documents
THERAPEUTIC USE OF LEVOROTATORY ?-LACTAMS IN HEMATOPOIESIS, IMMUNO-ONCOLOGY THERAPY, AND REGULATION OF LIPOPROTEIN AND APOLIPOPROTEIN LEVELS
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Paragraph 30-31, (2018/08/20)
A method for increasing the number of CD4+ T-lymphocytes in the serum of a subject in need of such treatment comprising administering to the subject a pharmaceutical composition comprising an amount of an L-isomer of β-lactam effective to increase the number of CD4+ T-lymphocytes in said patient's serum.
Amino ester hydrolase from Xanthomonas campestris pv. campestris, ATCC 33913 for enzymatic synthesis of ampicillin
Blum, Janna K.,Bommarius, Andreas S.
experimental part, p. 21 - 28 (2010/12/19)
α-Amino ester hydrolases (AEH) are a small class of proteins, which are highly specific for hydrolysis or synthesis of α-amino containing amides and esters including β-lactam antibiotics such as ampicillin, amoxicillin, and cephalexin. A BLAST search revealed the sequence of a putative glutaryl 7-aminocephalosporanic acid (GL-7-ACA) acylase 93% identical to a known AEH from Xanthomonas citri. The gene, termed gaa, was cloned from the genomic DNA of Xanthomonas campestris pv. campestris sp. strain ATCC 33913 and the corresponding protein was expressed into Escherichia coli. The purified protein was able to perform both hydrolysis and synthesis of a variety of α-amino β-lactam antibiotics including (R)-ampicillin and cephalexin, with optimal ampicillin hydrolytic activity at 25 °C and pH 6.8, with kinetic parameters of kcat of 72.5 s-1 and KM of 1.1 mM. The synthesis parameters α, βo, and γ for ampicillin, determined here first for this class of proteins, are α = 0.25, βo = 42.8 M-1, and γ = 0.23, and demonstrate the excellent synthetic potential of these enzymes. An extensive study of site-directed mutations around the binding pocket of X. campestris pv. campestris AEH strongly suggests that mutation of almost any first-shell amino acid residues around the active site leads to inactive enzyme, including Y82, Y175, D207, D208, W209, Y222, and E309, in addition to those residues forming the catalytic triad, S174, H340, and D307.
Chemical reactivity of penicillins and cephalosporins. Intramolecular involvement of the acyl-amido side chain
Llinas, Antonio,Vilanova, Bartolome,Frau, Juan,Munoz, Francisco,Donoso, Josefa,Page, Michael I.
, p. 9052 - 9060 (2007/10/03)
The rate of degradation of 6-epi-ampicillin in acidic, neutral, and alkaline aqueous solutions was followed at 35 °C and an ionic strength of 0.5 mol dm-3 (KCl) by high-performance liquid chromatography (HPLC) and spectrophotometric assays. Pseudo-first-order rate constants were determined in a variety of buffer solutions, and the overall pH-rate profile was obtained by extrapolation to zero buffer concentration. The hydrolysis of 6- epi-ampicillin is subject to acid and hydroxide-ion catalysis and, for a penicillin, an unusual pH-independent reaction. Intramolecular general base- catalyzed hydrolysis by the side chain amido group is proposed to explain the enhanced rate of neutral hydrolysis of 6-epi-ampicillin and cephalosporins. The β-lactam of 6-epi-ampicillin also undergoes intramolecular aminolysis by nucleophilic attack of the 6-α side chain amino group to give a stable piperazine-2,5-dione derivative. The low effective molarity for intramolecular aminolysis of only 40 M is partly attributed to the unfavorable trans to cis isomerization about the 6-amide side chain required for ring closure. Theoretical calculations show that the intramolecular aminolysis of 6-epi-ampicillin nucleophilic attack occurs from the α-face of the β-lactam ring with an activation energy of 14.4 kcal/mol.
Extremely Selective and Mild Cleavage of β-Haloalkyl Groups by Cobalt(I)phthalocyanine Anion in Semisyntheses of β-Lactam Antibiotics
Eckert, Heiner
, p. 1715 - 1724 (2007/10/02)
Cleavage of β-haloalkyl groups can be performed extremely selectively by cobalt(I)phthalocyanine anion under very mild conditions, qualifying it best in the chemistry of highly sensitive β-lactam antibiotics.This is demonstrated in penicillin and cephalosporin semisyntheses.