Surface modification of proteins activation of monomethoxy-polyethylene glycols by phenylchloroformates and modification of ribonuclease and superoxide dismutase

Abstract

A single-step method of activation of monomethoxypolyethylene glycols suitable for its binding to polypeptides and proteins is proposed. Based on the reaction with 2,4,5-trichlorophenylchloroformate or p-nitrophenylchloroformate, it gives reactive PEG-phenylcarbonate derivatives. The PEG intermediate is stable on storage, the activating group is easily quantified,and the reaction with amino acid and proteins proceeds rapidly at pH near neutrality. The PEG derivatization of enzymes with this procedure is less inactivating than those previously reported. Ribonuclease and superoxide dismutase were modified and the effect of (a) bound polymer on clearance time in rats, (b) antibody recognition, and (c) on the enzymatic activity toward low and high molecular weight substrates were studied.

“Stealth” Adenoviruses Blunt Cell-Mediated and Humoral Immune Responses against the Virus and Allow for Significant Gene Expression upon Readministration in the Lung

“…While these results are consistent with decreased CTL, it suggests that there may be a switch in the qualitative nature of the B-cell response from Th1 to Th2 dependent. There have been documented toxicities associated with PEGs activated by cyanuric chloride in which the triazine rings of the activating group stimulate Th2 responses (9,49). This type of response could account for the failure of the PEGylated viruses to produce significant levels of gene expression in animals immunized with the same modified virus (Fig.…”

Modulating the pharmacokinetics of therapeutic antibodies

“…When comparing various conjugation ratios using 2, 5, 10, 12 and 20 kDa polymers linked to either primary amines or carboxylic acids, Lee et al found that an increase in polymer length was found to be more effective for extending serum halflife than using a corresponding increase in total PEG by using smaller polymer lengths at a higher conjugation ratio (Lee et al 1999). These studies agree Reactivity & Characteristics PEG Carbonyl-Imidazole (Beauchamp et al, 1983;Veronese et al, 1985) N-terminal α-amines and lysine ε-amine group acylation leading to formation of carbamate linkages.…”

Solubilization of Hydrophobic Peptides by Reversible Cysteine PEGylation

“…This as well as the toxicity of the derivative and its promiscuous reactivity with the side chains of Cys and Tyr (Zalipsky et al, 1992) provided the impetus for the discovery of new chemistries of PEG denvatization. (Beauchamp et al, 1983) and MPEGphenylcarbonate (Veronese et al, 1985) were less promiscuous than the cyanuric chloriâe derivative, but suffered ffom poor reactivity and reagent toxicity, respectively. MPEG-succinirnidyl succinate (Abuchowski et al, 1984) and MPEG-succinimidyl carbonate (Zalipsky et al, 1992) exhibit high reactivity and specificity.…”