Work

Tuning C-Phycocyanin Photoactivity via pH-Mediated Assembly–Disassembly

Year: 2021

Type: article

Abstract: Environment-triggered protein conformational changes have garnered wide interest in both fundamental research, for deciphering in vivo acclimatory responses, and practical applications, for designing stimuli-responsive probes. Here, we propose a protein–chromophore regulatory mechanism that allows for manipulation of C-phycocyanin (C-PC) from Spirulina platensis by environmental pH and UV irradiation. Using small-angle X-ray scattering, a pH-mediated C-PC assembly–disassembly pathway, from monomers to nonamers, was unraveled. Such flexible protein matrices impart tunability to the embedded tetrapyrroles, whose photochemical behaviors were found to be modulated by protein assembly states. UV irradiation on C-PC triggers pH-dependent singlet oxygen ( 1 O 2 ) generation and conformational changes. Intermolecular photo-crosslinking occurs at pH 5.0 via dityrosine species, which bridges solution-based C-PC oligomers into unprecedented dodecamers and 24-mers. These supramolecular assemblies impart C-PC at pH 5.0, which significantly enhanced 1 O 2 yield, fluorescence, and photostability relative to those at other pH values, a finding that makes C-PC appealing for tumor-targeted photodynamic therapy.

Source: Biomacromolecules

DOI: 10.1021/acs.biomac.1c01095

Authors: Ying Li, Richard Gillilan, Alireza Abbaspourrad

Institutions: Cornell University, New York State College of Agriculture & Life Sciences, Cornell High Energy Synchrotron Source

Language: English

Topic: Porphyrin and Phthalocyanine Chemistry

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: green

Funders: National Institute of Food and Agriculture, National Institute of General Medical Sciences

Awards: G3649821697, National Biomedical Center for Advanced ESR Technology (ACERT), MacCHESS Synchrotron Source for Structural Biology