Identifying reducing and capping sites of protein-encapsulated gold nanoclusters

Yu Chen Hsu, Mei Jou Hung, Yi An Chen, Tsu Fan Wang, Ying Ru Ou, Shu-Hui Chen

Research output: Contribution to journalArticle

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Abstract

The reducing and capping sites along with their local structure impact photo properties of the red bovine serum albumin-capped Au nanocluster (BSA-AuNC), however, they are hard to identify. We developped a workflow and relevant techniques using mass spectrometry (MS) to identify the reducing and capping sites of BSA-AuNCs involved in their formation and fluorescence. Digestion without disulfide cleavages yielded an Au core fraction exhibiting red fluorescence and [AunSm] ion signals and a non-core fraction exhibiting neither of them. The core fraction was identified to mainly be comprised of peptides containing cysteine residues. The fluorescence and [AunSm] signals were quenched by tris(2-carboxyethyl)phosphine, confirming that disulfide groups were required for nanocluster stabilization and fluorescence. By MS sequencing, the disulfide pairs, C75–C91/C90–C101 in domain IA, C315–C360/C359–C368 in domain IIB, and C513–C558/C557–C566 in domain IIIB, were identified to be main capping sites of red AuNCs. Peptides containing oxidized cysteines (sulfinic or cysteic acid) were identified as reducing sites mainly in the non-core fraction, suggesting that disulfide cleavages by oxidization and conformational changes contributed to the subsequent growth of nanoclusters at nearby intact disulfide pairs. This is the first report on precise identification of the reducing and capping sites of BSA-AuNCs.

Original languageEnglish
Article number1630
JournalMolecules
Volume24
Issue number8
DOIs
Publication statusPublished - 2019 Apr 25

Fingerprint

Nanoclusters
disulfides
nanoclusters
Gold
Disulfides
gold
proteins
Fluorescence
fluorescence
cysteine
Proteins
peptides
Mass spectrometry
cleavage
Mass Spectrometry
mass spectroscopy
Cysteic Acid
Peptides
sequencing
Workflow

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Molecular Medicine
  • Pharmaceutical Science
  • Drug Discovery
  • Physical and Theoretical Chemistry
  • Organic Chemistry

Cite this

Hsu, Yu Chen ; Hung, Mei Jou ; Chen, Yi An ; Wang, Tsu Fan ; Ou, Ying Ru ; Chen, Shu-Hui. / Identifying reducing and capping sites of protein-encapsulated gold nanoclusters. In: Molecules. 2019 ; Vol. 24, No. 8.
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Identifying reducing and capping sites of protein-encapsulated gold nanoclusters. / Hsu, Yu Chen; Hung, Mei Jou; Chen, Yi An; Wang, Tsu Fan; Ou, Ying Ru; Chen, Shu-Hui.

In: Molecules, Vol. 24, No. 8, 1630, 25.04.2019.

Research output: Contribution to journalArticle

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