Radiation inactivation of galactose oxidase, a monomeric enzyme with a stable free radical.

To determine the radiation sensitivity of galactose oxidase, a 68 kDa monomeric enzyme containing a mononuclear copper ion coordinated with an unusually stable cysteinyl-tyrosine (Cys-Tyr) protein free radical. Both active enzyme and reversibly rendered inactive enzyme were irradiated in the frozen state with high-energy electrons. Surviving polypeptides and surviving enzyme activity were analyzed by radiation target theory giving the radiation sensitive mass for each property.

Identification of the active form of endothelial lipase, a homodimer in a head-to-tail conformation.

Endothelial lipase (EL) is a member of a subfamily of lipases that act on triglycerides and phospholipids in plasma lipoproteins, which also includes lipoprotein lipase and hepatic lipase. EL has a tropism for high density lipoprotein, and its level of phospholipase activity is similar to its level of triglyceride lipase activity. Inhibition or loss-of-function of EL in mice results in an increase in high density lipoprotein cholesterol, making it a potential therapeutic target.

The functional molecular mass of the Pasteurella hyaluronan synthase is a monomer.

Hyaluronan (HA), a linear polysaccharide composed of beta1,3-GlcNAc-beta1,4-GlcUA repeats, is found in the extracellular matrix of vertebrate tissues as well as the capsule of several pathogenic bacteria. All known HA synthases (HASs) are dual-action glycosyltransferases that catalyze the addition of two different sugars from UDP-linked precursors to the growing HA chain. The bacterial hyaluronan synthase, PmHAS from Gram-negative Pasteurella multocida, is a 972-residue membrane-associated protein.

Functional molecular mass of Escherichia coli K92 polysialyltransferase as determined by radiation target analysis.

The polysialyltransferase of Escherichia coli K92 catalyzes the transfer of sialic acid from CMP-sialic acid to a growing chain of polysialic acid at the nonreducing end. The enzyme encoded by the neuS gene is membrane-associated and has been suggested to be organized within a complex of several proteins encoded by the K92 gene cluster. Attempts to prepare a soluble active NeuS enzyme have been unsuccessful.

Radiation target analyses of DNA template/primer complexes.

Frozen solutions of low molecular weight DNA template/primer complexes, in the absence and presence of HIV-1 reverse transcriptase, were irradiated with high-energy electrons. Molecules that survived the radiation exposure were quantified and analyzed using radiation target theory. Transfer of radiation-deposited energy was observed by the damage caused.