Meeting Abstract
P1.55 Saturday, Jan. 4 15:30 Oxygen-binding properties of purified hemocyanin oligomers in penaeid shrimp WANG, J.*; JANECH, M.G.; BURNETT, L.E.; BURNETT, K.G.; College of Charleston; Medical University of South Carolina; College of Charleston; College of Charleston jasonwang103@gmail.com
The respiratory pigment hemocyanin (Hc) is the most abundant protein in penaeid shrimp hemolymph. Hc is composed of subunits arranged as n×6-oligomers which have intrinsic, species-specific properties. Along with extrinsic allosteric factors such as pH and lactate, the intrinsic oligomeric structure of Hc may influence O2-binding. Regulation of intrinsic and extrinsic factors is important in estuaries and aquaculture where O2, CO2, pH, and other factors fluctuate widely. The Pacific whiteleg shrimp, Litopenaeus vannamei, is farmed globally. Its Hc binds O2 more tightly (higher affinity) than other penaeid shrimps, including the brown shrimp Farfantepenaeus aztecus. Previous studies have shown that Hc 2×6-mers (dodecamers) are more abundant than 1×6-mers (hexamers) in L. vannamei hemolymph. The goal of this study is to compare O2-binding properties of purified hexamers and dodecamers in L. vannamei and F. aztecus. We hypothesize that Hc will occur mostly as high affinity dodecamers in L. vannamei compared to low affinity hexamers in F. aztecus hemolymph. We have purified Hc oligomers using a BioSepTM SEC-s3000 column (Phenomenex); O2-binding properties of isolated oligomers are measured tonometrically. The Cu-O2 complexes in Hc absorb at 338 nm and represent the dominant protein peaks observed in hemolymph. Only one dominant band, migrating at the molecular weight of a hexamer (~400 kDa) is detected in L. vannamei hemolymph by BN-PAGE at pH 7.5 while two dominant bands are seen for F. aztecus. SEC-HPLC appears to be a more reliable approach for Hc separation. Understanding the intrinsic O2 binding properties of Hc oligomers may provide insight into the success of L. vannamei in aquaculture. (NSF IOS-1147008)
