A gene encoding biodegradative ornithine decarboxylase from Lactobacillus sp. strain 30a was isolated from a genomic DNA library and sequenced. Primer extension analysis revealed two transcription initiation sites. The deduced amino acid sequence is compared with the amino acid sequences of five previously reported bacterial decarboxylases, and conserved pyridoxal phosphate motif residues are identified.

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Crude oil films on water are dissolved by photocatalytic oxidation. The photocatalyst, titanium dioxide, when excited by near-ultraviolet light, accelerates the oxidation of both the alipathic and the aromatic components of crude oil. The photocatalyst is maintained at the air-oil interface through attachment to sandlike ceramic microbeads that are hollow and buoyant. Experiments in the laboratory show that the near-ultraviolet solar irradiance is not rate limiting in the 25 to 50 W/m2 range. Thus the rate of cleanup is not expected to vary with season or latitude except in the Arctic winter. The projected cleanup times range from one week to several months. Times are shorter when larger amounts of beads are applied per barrel of oil and when the beads are smaller, more buoyant, or less aggregated by the oil. The rate of cleanup was found to be limited by oxygen mass transport and was accelerated by waves. Photocatalytic oxidation of crude oil, like natural noncatalytic oxidation, results in elimination of polycyclic aromatic hydrocarbons, some of which are carcinogens. Both the natural and the photocatalytic processes oxidize the aromatic hydrocarbons to phenols. However, the phenols are more rapidly eliminated in the photocatalytic reaction than they are in the natural photooxidation process.

An enzyme that catalyzes the hydrolysis of both glutamine and asparagine has been purified to homogeneity from extracts of Pseudomonas acidovorans. The enzyme having a ratio of glutaminase to asparaginase of 1.45:1.0 can be purified by a relatively simple procedure and is stable upon storage. The glutaminase-asparaginase has a relatively high affinity for-asparagine (K,,, = 1.5 x 10-5 M) and L-glutamine (K,, = 2.2 x 10-5 M) and has a molecular weight of approximately 156,000, the subunit molecular weight being approximately 39,000. Injections of the enzyme produced only slight increases in the survival time of C3H/HE mice carrying the asparagine-requiring 6C3HED Gardner lymphoma and of white Swiss mice carrying the glutamine-requiring Ehrlich lymphoma.'

A nucleotide effector site of the biodegradative form of ornithine decarboxylase from Lactobacillus 30a (OrnDC L30a) has been identified. OrnDC L30a activity at pH 8.0, where the enzyme is normally inactive, is stimulated by GTP and dGTP and to a lesser extent by GDP but not by ATP, CTP, or UTP. The pH profile indicates that activation by GTP is reflected by an increase in k cat/K M,orn (above pH 6.8), while V max remains constant over the pH range 4.0−9.0. Scatchard plot analysis shows that GTP binds to OrnDC L30a at both pH 5.8 (K D = 0.11 μM) and pH 8.0 (K D = 1.6 μM), but unexpectedly, half-site binding is observed at the higher pH. The OrnDC L30a dodecamer dissociates into dimers at high pH in the presence or absence of GTP. The GTP binding site was located in difference electron density maps using low-resolution X-ray data. This represents a new type of GTP binding site. A model explaining the activation of OrnDC L30a by GTP is presented.