Protein renaturation is of particular interest not only for the basic
mechanisms of protein folding but also as a practical problem for prot
eins overexpressed in microorganisms, since recombinant proteins may a
ccumulate as misfolded aggregates in ''inclusion bodies'' that are ina
ctive after purification. We have established a systematic screening m
ethod to identify conditions which promote protein renaturation. A mat
rix of 50 different buffers, which were originally developed for prote
in crystallization, were found to facilitate the renaturation for eigh
t of nine different proteins examined. The proteins tested include the
adhesive protein bindin, recombinant bindin, and a variety of enzymes
, including bacterial alkaline phophatase, horseradish peroxidase, lys
ozyme, trypsin, beta-galactosidase, rabbit carboxylesterase, and acety
lcholinesterase. The total amount of activity recovered varied hom 9 t
o 333% depending on the protein. The conditions that were found to pro
mote renaturation are very different from the optimal conditions for e
nzyme activity. The finding that most of the proteins tested renatured
to a significant extent in one or more of the buffers in the matrix s
uggests that the sparse matrix screen may be of general utility for es
tablishing initial renaturation conditions for a wide variety of prote
ins. Once initial renaturation conditions have been identified, the co
nditions may be optimized by systematically altering other parameters
of the renaturation process. (C) 1995 Academic Press, Inc.