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Secondary structure and limited proteolysis give experimental evidence that the precursor of pulmonary surfactant protein B contains three saposin‐like domains
Author(s) -
Zaltash Shahparak,
Johansson Jan
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)01582-2
Subject(s) - pulmonary surfactant , proteolysis , recombinant dna , escherichia coli , residue (chemistry) , biochemistry , chemistry , inclusion bodies , surfactant protein c , biology , enzyme , gene
The 42 kDa precursor of surfactant protein B generates the 79 residue mature SP‐B polypeptide, which belongs to the family of saposin‐like proteins and has unique functional roles in pulmonary surfactant. From sequence comparisons it has been suggested that proSP‐B, in addition to SP‐B, contains two saposin‐like domains, but their existence has until now not been experimentally verified. The 381 residue human proSP‐B was now fused to an N‐terminal poly‐His tag, expressed in Escherichia coli , and purified from inclusion bodies by resolubilisation with 2.5% (w/v) SDS and, after removal of SDS, subsequent metal affinity chromatography. Recombinant proSP‐B thus obtained exhibits about 35% α‐helical structure in sodium phosphate buffer and is proteolytically cleaved preferentially between the three saposin‐like domains. These results experimentally support that proSP contains, in addition to SP‐B, two further saposin‐like domains.