Publications

• Swinging arms and swinging domains in multifunctional enzymes: catalytic machines for multistep reactions.

  Perham R.N.

  Multistep chemical reactions are increasingly seen as important in a growing number of complex biotransformations. Covalently attached prosthetic groups or swinging arms, and their associated protein domains, are essential to the mechanisms of active-site coupling and substrate channeling in a num ... >> More

  Multistep chemical reactions are increasingly seen as important in a growing number of complex biotransformations. Covalently attached prosthetic groups or swinging arms, and their associated protein domains, are essential to the mechanisms of active-site coupling and substrate channeling in a number of the multifunctional enzyme systems responsible. The protein domains, for which the posttranslational machinery in the cell is highly specific, are crucially important, contributing to the processes of molecular recognition that define and protect the substrates and the catalytic intermediates. The domains have novel folds and move by virtue of conformationally flexible linker regions that tether them to other components of their respective multienzyme complexes. Structural and mechanistic imperatives are becoming apparent as the assembly pathways and the coupling of multistep reactions catalyzed by these dauntingly complex molecular machines are unraveled. << Less

  Annu Rev Biochem 69:961-1004(2000) [PubMed] [EuropePMC]

  This publication is cited by 6 other entries.

• Expression, purification, and physical characterization of Escherichia coli lipoyl(octanoyl)transferase.

  Nesbitt N.M., Baleanu-Gogonea C., Cicchillo R.M., Goodson K., Iwig D.F., Broadwater J.A., Haas J.A., Fox B.G., Booker S.J.

  Lipoic acid is a sulfur-containing 8-carbon fatty acid that functions as a central cofactor in multienzyme complexes that are involved in the oxidative decarboxylation of glycine and several alpha-keto acids. In its functional form, it is bound covalently in an amide linkage to the epsilon-amino g ... >> More

  Lipoic acid is a sulfur-containing 8-carbon fatty acid that functions as a central cofactor in multienzyme complexes that are involved in the oxidative decarboxylation of glycine and several alpha-keto acids. In its functional form, it is bound covalently in an amide linkage to the epsilon-amino group of a conserved lysine residue of the "lipoyl bearing subunit," resulting in a long "swinging arm" that shuttles intermediates among the requisite active sites. In Escherichia coli and many other organisms, the lipoyl cofactor can be synthesized endogenously. The 8-carbon fatty-acyl chain is constructed via the type II fatty acid biosynthetic pathway as an appendage to the acyl carrier protein (ACP). Lipoyl(octanoyl)transferase (LipB) transfers the octanoyl chain from ACP to the target lysine acceptor, generating the substrate for lipoyl synthase (LS), which subsequently catalyzes insertion of both sulfur atoms into the C-6 and C-8 positions of the octanoyl chain. In this study, we present a three-step isolation procedure that results in a 14-fold purification of LipB to >95% homogeneity in an overall yield of 25%. We also show that the protein catalyzes the transfer of the octanoyl group from octanoyl-ACP to apo-H protein, which is the lipoyl bearing subunit of the glycine cleavage system. The specific activity of the purified protein is 0.541 U mg(-1), indicating a turnover number of approximately 0.2 s(-1), and the apparent Km values for octanoyl-ACP and apo-H protein are 10.2+/-4.4 and 13.2+/-2.9 microM, respectively. << Less

  Protein Expr. Purif. 39:269-282(2005) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• The mitochondrial glycine cleavage system. Functional association of glycine decarboxylase and aminomethyl carrier protein.

  Hiraga K., Kikuchi G.

  J. Biol. Chem. 255:11671-11676(1980) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.