tailieunhanh - Báo cáo khoa học: Structure and function comparison of Micropechis ikaheka snake venom phospholipase A2 isoenzymes

Comparison of the crystal structures of threeMicropechis ikahekaphos-pholipase A2 isoenzymes (MiPLA2, MiPLA3 and MiPLA4, which exhibit different levels of pharmacological effects) shows that their C-terminus (residues 110–124) is the most variable. M-Type receptor binding affinity of the isoenzymes has also been investigated and MiPLA4 binds to the rabbit M-type receptor with high affinity. Examination of surface charges of the isoenzymes reveals a trend of increase in positive charges with potency | ềFEBS Journal Structure and function comparison of Micropechis ikaheka snake venom phospholipase A2 isoenzymes Shee-Mei Lok1 Rong Gao1 2 Morgane Rouault4 Gerard Lambeau4 Ponnampalam Gopalakrishnakone2 and Kunchithapadam Swaminathan1 3 1 Institute of Molecular and CellBiology Singapore 2 Department of Anatomy NationalUniversity of Singapore Singapore 3 Department of BiologicalSciences NationalUniversity of Singapore Singapore 4 Institut de Pharmacologie Moleculaire et Cellulaire CNRS-UMR 6097 Valbonne France Keywords group IB phospholipase A2 pharmacological determinant crystal structure Micropechis ikaheka Correspondence Kunchithapadam Swaminathan Institute of Molecular and Cell Biology 61 Biopolis Drive Singapore 138673 Fax 65 67791117 Tel 65 65869697 E-mail nathan@ Received 15 September 2004 revised 23 November 2004 accepted 5 January 2005 doi Comparison of the crystal structures of three Micropechis ikaheka phospholipase A2 isoenzymes MÌPLA2 MÌPLA3 and MÌPLA4 which exhibit different levels of pharmacological effects shows that their C-terminus residues 110-124 is the most variable. M-Type receptor binding affinity of the isoenzymes has also been investigated and MiPLA4 binds to the rabbit M-type receptor with high affinity. Examination of surface charges of the isoenzymes reveals a trend of increase in positive charges with potency. The isoenzymes are shown to oligomerize in a concentrationdependent manner in a semi-denaturing gel. The C-termini of the medium MiPLA4 and highly potent MiPLA2 isoenzyme molecules cluster together forming a highly exposed area. A BLAST search using the sequence of the most potent MiPLA2 results in high similarity to Staphylococcus aureus clotting factor A and cadherin 11. This might explain the myotoxicity anticoagulant and hemoglobinuria effects of MiPLA2s. Secreted phospholipase A2 sPLA2 is a stable and compact enzyme about 125 residues with five to eight intramolecular disulfide