Open AccessStructure of Protocollagen Proline Hydroxylase from Chick Embryos
Author(s) -
Olsen Bjørn R.,
Berg Richard A.,
Kivirikko Kari I.,
Prockop Darwin J.
Publication year - 1973
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1973.tb02819.x
Subject(s) - tetramer , monomer , electron microscope , enzyme , ring (chemistry) , proline , chemistry , crystallography , stereochemistry , biochemistry , amino acid , polymer , organic chemistry , physics , optics
Protocollagen proline hydroxylase was purified from chick embryos with an affinity‐column procedure which yielded pure enzyme in a tetramer form. Electron microscopy of the enzyme after it was largely dissociated into monomers indicated that the monomers were rod‐shaped with a diameter of 3.31 ± 0.07 nm (S.E.M.) and a length of 6.95 ± 0.07 nm. In preparations of the enzyme in which the protein was partially dissociated, dumb‐bell and V‐shaped structures were seen which morphologically consisted of two sub‐structures each with dimensions similar to those of the isolated monomers. The results suggested that these structures were dimers in which the monomers were joined at one end with an angle between their longitudinal axes. The largest regular protein structures seen in preparations of the enzyme were about 8 × 8 nm and in some of these structures four sub‐structures were seen, indicating that they were tetramers. On the basis of the data presented here we propose a model of the tetramer in which two V‐shaped dimers were interlocked. Further studies demonstrated that the single‐ring and four‐ring structures seen by electron microscopy of enzyme preparations obtained by a previous purification procedure were not the enzyme.