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Muraoka A, Matsuura Y, Naitow H, Ihara M, Kunishima N. Availability of NHS-biotin labeling to identify free protein lysine revealed by experiment and MD simulation. Anal Biochem 2018; 557:46-58. [PMID: 30025973 DOI: 10.1016/j.ab.2018.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 07/04/2018] [Accepted: 07/13/2018] [Indexed: 11/27/2022]
Abstract
It is known that the crystallizability of protein molecules may be improved by replacing their surface lysine residues with other residue types. Here an experimental method to identify surface lysine residues by NHS-biotin chemical modification combined with MALDI-TOF MS was proposed and was evaluated using PH1033 protein from Pyrococcus horikoshii. Interestingly, the biotinylation experiment with a protein-reagent molar ratio of 1:1 revealed that only seven of twenty-two lysine residues in the protein comprising 144 residues were labeled. To investigate the result, we analyzed structures from a molecular-dynamics simulation mimicking the experiment. A logistic regression analysis revealed that the biotinylation was significantly correlated with four factors relevant to the local environment of lysine residues: the solvent accessibility, the electrostatic energy, the number of hydrogen bonds, and the estimated pKa value. This result is overall in agreement with that from the same analysis on the crystal structure. However, reflecting the flexibility of the protein molecule in solution state, the factors except for the electrostatic energy were highly variable in the MD structures depending upon the protonation state of Tyr87. The present procedure of biotin-labeling can avoid lysine residues with extensive intramolecular interactions that are incompatible with the rational design of protein crystals.
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Affiliation(s)
- Aiichiro Muraoka
- Bio-Specimen Platform Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Yoshinori Matsuura
- Bio-Specimen Platform Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Hisashi Naitow
- Bio-Specimen Platform Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Makoto Ihara
- Bio-Specimen Platform Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan; Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara City, Nara 631-8505, Japan
| | - Naoki Kunishima
- Bio-Specimen Platform Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan; RIKEN RSC-Rigaku Collaboration Center, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
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