Philippine Journal of Science
147 (1): 65-74, March 2018
ISSN 0031 – 7683
Date Received: 07 Apr 2017

Biophysical and Functional Characterization of asFP504,
a Novel Fluorescent Protein from the Philippines

Neil Andrew D. Bascos1^,*, Francine Lianne C. Emralino¹, Franco Carlos Liu¹,
Carla P. Concepcion², Marvin Altamia², Yen-Chieh Huang³, Yin-Cheng Hsieh³,
Chun-Jung Chen^3,4,5,*, and Cynthia Palmes-Saloma^2,*

¹Protein Structure and Immunology Laboratory, National Institute of Molecular Biology and Biotechnology,
University of the Philippines Diliman, Quezon City, Philippines
²Laboratory of Molecular and Cellular Biology, National Institute of
Molecular Biology and Biotechnology, University of the Philippines Diliman, Quezon City, Philippines
³Life Science Group, Scientific Research Division,
National Synchrotron Radiation Research Center, Hsinchu, Taiwan
⁴Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
5Institute of Biotechnology, University Center for Bioscience and
Biotechnology, National Cheng Kung University, Tainan, Taiwan

*Corresponding authors: neilandrew.bascos@mbb.upd.edu.ph
cpsaloma@mbb.upd.edu.ph
cjchen@nsrrc.org.tw

 

ABSTRACT

Fluorescent proteins have proven to be invaluable for a myriad of applications in scientific research. The discovery and characterization of novel fluorescent proteins promises to expand this range even further. This report focuses on the biophysical and functional characterization of a novel green fluorescent protein cloned from a Philippine soft coral species. The asFP504 protein showed peak excitation at 471 nm and at 494 nm (λE1= 471 nm; λE2=494 nm), its emission maximum from 471 nm excitation was observed at 504 nm. The fluorescence was observed to be related to its oligomeric state. Both fluorescence and oligomerization were robustly maintained for a range of temperatures, pH conditions, treatment with chaotropic agents, and proteolysis. X-ray crystallography documented a molecular packing of three dimers within each asymmetric unit for the asFP504 protein. The observed absorbance and fluorescence properties are comparable to that of commercially available fluorescence proteins. Despite its lower absorbance, asFP504 has higher quantum yield than mCitrine. In addition, the stability of asFP504 in the presence of multiple denaturants presents the potential of this protein – the first fluorescent protein from the Philippines – for use in many different research applications.