Ethanol Release Research Articles

Sustained release of alcohol: subcutaneous silastic implants in mice.

A sustained-release device for use in ethanol dependence studies in mice is described. The Silastic device, dubbed SERT (sustained ethanol release tube), holds 0.35 milliliter of 95 percent ethanol (by volume) and is implanted under the skin of the back where it releases ethanol for up to 12 hours, with no observable tissue damage. The device may be adaptable to the release of other volatile liquids or drugs, in other animals.

Interaction of Peroxidases with Aromatic Peracids and Alkyl Peroxides: PRODUCT ANALYSIS

Abstract Two limiting structures may be assigned to the primary derivative of peroxidases (Compound I) demanding either (a) total or (b) partial retention of peroxide components. It is now shown that (a) interaction of horseradish peroxidase with m-nitroperbenzoic acid, in 15 mm phosphate, pH 6.2, 25°, leads to the stoichiometric formation of the enzyme-peroxide derivative, m-nitrobenzoate and 1 proton; and (b) in 5 mm phosphate, pH 6.6, 10°, the conversion of horseradish peroxidase into Compound I with ethyl hydrogen peroxide, is attended by the release of ethanol, but without concomitant prototropic changes. The results establish that horseradish peroxidase (H-peroxidase) Compound I is not an enzyme peroxide complex, but a derivative in which the active site is oxidized. The optical spectra of H-peroxidase and Compound I in 5 mm phosphate, pH 6.6, 25°, were re-examined and extended to include previously undefined features in the near infrared absorption region. The spectrum of Compound I is devoid of bands typical of isoporphyrins, suggesting that conversion of the enzyme into Compound I does not involve covalent modification of the prosthetic group.

Optical and chemical identification of kinetic steps in trypsin- and chymotrypsin-catalysed reactions.

Previous interpretations of the mechanism of trypsin- and chymotrypsin-catalysed reactions in terms of two intermediates, the Michaelis complex and an acyl-enzyme, were based on steady-state studies and on the observation of individual steps under sub-optimum conditions. In the present paper new methods for the rapid analysis of chemical events and for the spectrophotometric detection of individual steps are applied to these two enzymes. These methods can be used to study reactions with specific amino acid ester substrates. It can be shown that there are at least three distinct steps between the Michaelis complex and the release of ethanol; the latter is likely to correspond to acyl-enzyme formation. The relative rates of these three steps are measured by rapid-flow techniques from observations of the displacement of chromophoric inhibitors and reactions with specific substrates containing chromophores, as well as from ethanol analyses during a single turnover of the enzyme reactions. It is concluded that the reactions of trypsin and chymotrypsin with their specific substrates involve the formation of a specially reactive conformation of the enzyme-substrate complex and that the rate constants involved in this rearrangement are at least as important for the overall reaction as those of the subsequent formation and decomposition of the acyl-enzyme.

The α-chymotrypsin catalyzed hydrolysis of ethyl lactate

The pH dependence (pH 5.2–8.6) of k 3 0 and K s 0 for the α-chymotrypsin-catalyzed hydrolysis of ethyl dl-lactate in 0.10 M NaCl at 25 °C. has been determined. The value of k 3 0 first increases with pH; reaches a maximum of 0.039 sec. −1 at pH 7.8; then, decreases. The value of K s 0 decreases from 0.46 to 0.11 M with increasing pH. The kinetics have been discussed in terms of a mechanism involving three enzyme-substrate complexes. It has been tentatively concluded that the rate-determining step for ethyl lactate is the ester interchange leading to the formation of enzyme-serine lactate and the release of ethanol. A value of p K a = 6.7 was obtained for the active imidazolium group to which the lactyl is transferred before hydrolysis.