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Goldberg AM, Robinson MK, Starr ES, Marasco RN, Alana AC, Cochrane CS, Klugh KL, Strzeminski DJ, Du M, Colabroy KL, Peterson LW. L-DOPA Dioxygenase Activity on 6-Substituted Dopamine Analogues. Biochemistry 2021; 60:2492-2507. [PMID: 34324302 DOI: 10.1021/acs.biochem.1c00310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dioxygenase enzymes are essential protein catalysts for the breakdown of catecholic rings, structural components of plant woody tissue. This powerful chemistry is used in nature to make antibiotics and other bioactive materials or degrade plant material, but we have a limited understanding of the breadth and depth of substrate space for these potent catalysts. Here we report steady-state and pre-steady-state kinetic analysis of dopamine derivatives substituted at the 6-position as substrates of L-DOPA dioxygenase, and an analysis of that activity as a function of the electron-withdrawing nature of the substituent. Steady-state and pre-steady-state kinetic data demonstrate the dopamines are impaired in binding and catalysis with respect to the cosubstrate molecular oxygen, which likely afforded spectroscopic observation of an early reaction intermediate, the semiquinone of dopamine. The reaction pathway of dopamine in the pre-steady state is consistent with a nonproductive mode of binding of oxygen at the active site. Despite these limitations, L-DOPA dioxygenase is capable of binding all of the dopamine derivatives and catalyzing multiple turnovers of ring cleavage for dopamine, 6-bromodopamine, 6-carboxydopamine, and 6-cyanodopamine. 6-Nitrodopamine was a single-turnover substrate. The variety of substrates accepted by the enzyme is consistent with an interplay of factors, including the capacity of the active site to bind large, negatively charged groups at the 6-position and the overall oxidizability of each catecholamine, and is indicative of the utility of extradiol cleavage in semisynthetic and bioremediation applications.
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Affiliation(s)
- Alexander M Goldberg
- Department of Chemistry, Muhlenberg College, 2400 Chew Street, Allentown, Pennsylvania 18104, United States
| | - Miranda K Robinson
- Department of Chemistry, Muhlenberg College, 2400 Chew Street, Allentown, Pennsylvania 18104, United States
| | - Erykah S Starr
- Department of Chemistry, Rhodes College, 2000 North Parkway, Memphis, Tennessee 38112, United States
| | - Ryan N Marasco
- Department of Chemistry, Rhodes College, 2000 North Parkway, Memphis, Tennessee 38112, United States
| | - Alexa C Alana
- Department of Chemistry, Rhodes College, 2000 North Parkway, Memphis, Tennessee 38112, United States
| | - C Skyler Cochrane
- Department of Chemistry, Rhodes College, 2000 North Parkway, Memphis, Tennessee 38112, United States
| | - Kameron L Klugh
- Department of Chemistry, Rhodes College, 2000 North Parkway, Memphis, Tennessee 38112, United States
| | - David J Strzeminski
- Department of Chemistry, Muhlenberg College, 2400 Chew Street, Allentown, Pennsylvania 18104, United States
| | - Muxue Du
- Department of Chemistry, Muhlenberg College, 2400 Chew Street, Allentown, Pennsylvania 18104, United States
| | - Keri L Colabroy
- Department of Chemistry, Muhlenberg College, 2400 Chew Street, Allentown, Pennsylvania 18104, United States
| | - Larryn W Peterson
- Department of Chemistry, Rhodes College, 2000 North Parkway, Memphis, Tennessee 38112, United States
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