Publications

• Refinement of the arginine kinase transition-state analogue complex at 1.2 A resolution: mechanistic insights.

  Yousef M.S., Fabiola F., Gattis J.L., Somasundaram T., Chapman M.S.

  The three-dimensional crystal structure of an arginine kinase transition-state analogue complex has been refined at 1.2 A resolution, with an overall R factor of 12.3%. The current model provides a unique opportunity to analyze the structure of a bimolecular (phosphagen kinase) enzyme in its trans ... >> More

  The three-dimensional crystal structure of an arginine kinase transition-state analogue complex has been refined at 1.2 A resolution, with an overall R factor of 12.3%. The current model provides a unique opportunity to analyze the structure of a bimolecular (phosphagen kinase) enzyme in its transition state. This atomic resolution structure confirms in-line transfer of the phosphoryl group and the catalytic importance of the precise alignment of the substrates. The structure is consistent with a concerted proton transfer that has been proposed for an unrelated kinase. Refinement of anisotropic temperature factors and translation-libration-screw (TLS) analyses led to the identification of four rigid groups and their prevalent modes of motion in the transition state. The relative magnitudes of the mobility of rigid groups are consistent with their proposed roles in catalysis. << Less

  Acta Crystallogr. D 58:2009-2017(2002) [PubMed] [EuropePMC]

• Proteomics and immunological analysis of a novel shrimp allergen, Pen m 2.

  Yu C.J., Lin Y.F., Chiang B.L., Chow L.P.

  Shellfish are a common cause of adverse food reactions in hypersensitive individuals and shrimp is one of the most frequently reported causes of allergic reactions. A novel allergen from Penaeus monodon, designated Pen m 2, was identified by two-dimensional immunoblotting using sera from subjects ... >> More

  Shellfish are a common cause of adverse food reactions in hypersensitive individuals and shrimp is one of the most frequently reported causes of allergic reactions. A novel allergen from Penaeus monodon, designated Pen m 2, was identified by two-dimensional immunoblotting using sera from subjects with shrimp allergy, followed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of the peptide digest. This novel allergen was then cloned and the amino acid sequence deduced from the cDNA sequence. The cloned cDNA encoded a 356-aa protein with an acetylated N terminus at Ala2, identified by postsource decay analysis. Comparison of the Pen m 2 sequence with known protein sequences revealed extensive similarity with arginine kinase (EC 2.7.3.3) from crustaceans. Pen m 2 was purified by anion exchange chromatography and shown to have arginine kinase activity and to react with serum IgE from shrimp allergic patients and induce immediate type skin reactions in sensitized patients. Using Pen m 2-specific antisera and polyclonal sera from shrimp-sensitive subjects in a competitive ELISA inhibition assay, Pen m 2 was identified as a novel cross-reactive Crustacea allergen. This novel allergen could be useful in allergy diagnosis and in the treatment of Crustacea-derived allergic disorders. << Less

  J. Immunol. 170:445-453(2003) [PubMed] [EuropePMC]

• Transition state structure of arginine kinase: implications for catalysis of bimolecular reactions.

  Zhou G., Somasundaram T., Blanc E., Parthasarathy G., Ellington W.R., Chapman M.S.

  Arginine kinase belongs to the family of enzymes, including creatine kinase, that catalyze the buffering of ATP in cells with fluctuating energy requirements and that has been a paradigm for classical enzymological studies. The 1.86-A resolution structure of its transition-state analog complex, re ... >> More

  Arginine kinase belongs to the family of enzymes, including creatine kinase, that catalyze the buffering of ATP in cells with fluctuating energy requirements and that has been a paradigm for classical enzymological studies. The 1.86-A resolution structure of its transition-state analog complex, reported here, reveals its active site and offers direct evidence for the importance of precise substrate alignment in the catalysis of bimolecular reactions, in contrast to the unimolecular reactions studied previously. In the transition-state analog complex studied here, a nitrate mimics the planar gamma-phosphoryl during associative in-line transfer between ATP and arginine. The active site is unperturbed, and the reactants are not constrained covalently as in a bisubstrate complex, so it is possible to measure how precisely they are pre-aligned by the enzyme. Alignment is exquisite. Entropic effects may contribute to catalysis, but the lone-pair orbitals are also aligned close enough to their optimal trajectories for orbital steering to be a factor during nucleophilic attack. The structure suggests that polarization, strain toward the transition state, and acid-base catalysis also contribute, but, in contrast to unimolecular enzyme reactions, their role appears to be secondary to substrate alignment in this bimolecular reaction. << Less

  Proc. Natl. Acad. Sci. U.S.A. 95:8449-8454(1998) [PubMed] [EuropePMC]