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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Improving Alternate Lignin Catabolite Utilization Of Ligab From Sphingobium Sp. Strain Syk-6 Through Site Directed Mutagenesis, Kevin P. Barry, Erin F. Cohn, Abraham Ngu, Erika A. Taylor Jun 2015

Improving Alternate Lignin Catabolite Utilization Of Ligab From Sphingobium Sp. Strain Syk-6 Through Site Directed Mutagenesis, Kevin P. Barry, Erin F. Cohn, Abraham Ngu, Erika A. Taylor

Erika A. Taylor, Ph.D.

Protocatechuate 4,5-dioxygenase (LigAB) catalyzes dioxygenation of multiple lignin derived aromatic compounds—such as protocatechuate (PCA), gallate (GA) and 3-O-methyl gallate (3OMG)—with decreasing proficiency as the molecule size increases. We predicted that phenylalanine-103 of the α subunit (Phe103α) controls substrate specificity through interaction with the C5-funtionality of bound substrates, and mutagenesis would enhance GA and 3OMG catalysis. LigAB with Phe103α mutations (F103 V, F103T and F103H) displayed enhanced catalytic efficiency for dioxygenation of 3OMG, with mutants displaying 12- to 31-fold increases in View the MathML source, making these mutant enzymes more active with 3OMG than its native dioxygenase (DesZ). The F103T and …


Sucralose Destabilization Of Protein Structure, Lee Chen, Nimesh Shukla, Inha Cho, Erin F. Cohn, Erika A. Taylor, Christina M. Othon Mar 2015

Sucralose Destabilization Of Protein Structure, Lee Chen, Nimesh Shukla, Inha Cho, Erin F. Cohn, Erika A. Taylor, Christina M. Othon

Erika A. Taylor, Ph.D.

Sucralose is a commonly employed artificial sweetener that behaves very differently than its natural disaccharide counterpart, sucrose, in terms of its interaction with biomolecules. The presence of sucralose in solution is found to destabilize the native structure of two model protein systems: the globular protein bovine serum albumin and an enzyme staphylococcal nuclease. The melting temperature of these proteins decreases as a linear function of sucralose concentration. We correlate this destabilization to the increased polarity of the molecule. The strongly polar nature is manifested as a large dielectric friction exerted on the excited-state rotational diffusion of tryptophan using time-resolved fluorescence …


Exploring Allosteric Activation Of Ligab From Sphingobium Sp. Strain Syk-6 Through Kinetics, Mutagenesis And Computational Studies, Kevin P. Barry, Jason P. Gerbino, Abraham Ngu, Erin F. Cohn, Joy M. Cote, A. Maxwell Burroughs, Erika A. Taylor Jan 2015

Exploring Allosteric Activation Of Ligab From Sphingobium Sp. Strain Syk-6 Through Kinetics, Mutagenesis And Computational Studies, Kevin P. Barry, Jason P. Gerbino, Abraham Ngu, Erin F. Cohn, Joy M. Cote, A. Maxwell Burroughs, Erika A. Taylor

Erika A. Taylor, Ph.D.

The protocatechuate 4,5-dioxygenase (LigAB) from Sphingobium sp. strain SYK-6 is the defining member of the Type II extradiol dioxygenase superfamily (a.k.a. PCA Dioxygenase Superfamily or PCADSF) and plays a key aromatic ring-opening role in the metabolism of several lignin derived aromatic compounds. In our search for alternate substrates and inhibitors of LigAB, we discovered allosteric rate enhancement in the presence of non-substrate protocatechuate-like aldehydes such as vanillin. LigAB has the broadest substrate utilization profile of all protocatechuate (PCA) 4,5-dioxygenase described in the literature, however, the rate enhancement is only observed with PCA, with vanillin increasing kcat for LigAB by 36%. …