TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The host cell is a plant cell or a fungal cell.    TECHNOLOGY FOCUS - BIOTECHNOLOGY - Recombinant Method (claimed): Preparation of the polypeptide (p1) having improved activity or stability compared to a parent or class of parent polypeptides, involves identifying evolutionary, structurally or evolutionary and structurally related polypeptides; selecting a set of crossover locations comprising N peptide segments in at least a first polypeptide and at least a second polypeptide of the related polypeptides; selecting a parent from the evolutionary, structurally or evolutionary and structurally related polypeptides having stable functional expression; generating chimeras comprising N-1 peptide segments from the parent and one heterologous peptide segment from one other polypeptide from the evolutionary, structurally or evolutionary and structurally related polypeptides; identifying improved chimeras having increased activity or stability and identifying the heterologous peptide segment as activity/stability-associated peptide segments in the improved monomeras; generating a sample set (xP') of recombined, recombinant proteins comprising an activity/stability-associated peptide segments from each of the at least first polypeptide and second polypeptide, where x is less than 1; measuring stability of the sample set of expressed-folded recombined, recombinant proteins; and generating chimera polypeptides comprising activity/stability-associated peptide segments. The improved chimeras are identified by performing regression analysis. The step of selecting a set of crossover locations involves aligning the sequences of the evolutionary, structurally or evolutionary and structurally related polypeptides and identifying regions of identity of the sequences. The method involves sequence alignment and methods selected from X-ray crystallography, NMR, searching a protein structure database, homology modeling, de novo protein folding, and computational protein structure prediction. The step of selecting a set of crossover locations involves: identifying coupling interactions between pairs of residues in the at least first polypeptide; generating data structures, each representing a crossover mutant comprising a recombination of the first and second polypeptide, where each recombination has a different crossover location; determining, for each data structure, a crossover disruption related to the number of coupling interactions disrupted in the crossover mutant represented by the data structure; and identifying, among the data structures, a particular data structure having a crossover disruption below a threshold, where the crossover location of the crossover mutant represented by the particular data structure is the identified crossover location, where coupling interactions are identified by a determination of a conformational energy or interatomic distances between residues. The conformational energies for each of the first and second polypeptides are determined from a three-dimensional structure for at least one of the first and second polypeptides. The interatomic distances are determined from a three-dimensional structure of at least one polypeptide of the polypeptides. The coupling interactions are identified by a conformational energy between residues above a threshold. The threshold is an average level of crossover disruption for the data structures. The identification of crossover location involves identification of possible cut points in the polypeptide based upon regions of sequence identity. The regions of sequence identity must contain at least 4 residues. The step of measuring stability involves techniques selected from chemical stability measurements, functional stability measurements, and thermal stability measurements comprising chemical denaturation measurements (preferably thermal denaturation measurements). The function stability measurement comprises ligand or substrate binding techniques. The regression analysis involves determining sequence-stability data or consensus analysis of several sequence alignment (MSA) of folded versus unfolded proteins, where the sequence-stability data comprises sequence information operably associated with stability measurements. The method further involves creating monomera with fragments of a peptide segment. The parent comprises a sequence having at least 80%-100% identity to (SEQ ID NO: 15) as available on WIPO website. Preferred Polypeptide: The polypeptide (p1) is at least 60-100% identical to a sequence selected from (SEQ ID NO: 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 and 34) all as available on WIPO website; comprises a leader sequence in operable linkage to the N-terminal amino acid; and further comprises a C-terminal CBM domain comprising a sequence selected from (SEQ ID NO: 16, 17 and 18) as available on WIPO website. The two different parental cellobiohydrolase I (CBHI) polypeptides comprise sequences selected from (SEQ ID NO: 2, 4, 6, 8 and 10). The enzymatic preparation further comprises a thermostabilized cellobiohydrolase class II enzymatic chimera. Preferred Definitions:    s1=segment comprising amino acid residue from 1 or 18 or 19 to x1 of T1 and having 1-10 conservative amino acid substitutions;    s2=segment which is an amino acid residue x1 to x2 of T1 and having 1-10 conservative amino acid substitutions;    s3=segment which is an amino acid residue x2 to x3 of T1 and having 1-10 conservative amino acid substitutions;    s4=segment which is amino acid residue x3 to x4 of T1 and having 1-10 conservative amino acid substitutions;    s5=segment which is amino acid residue x4 to x5 of T1 and having 1-10 conservative amino acid substitutions;    s6=segment which is amino acid residue x5 to x6 of T1 and having 1-10 conservative amino acid substitutions;    s7=segment which is amino acid residue x6 to x7 of T1 and having 1-10 conservative amino acid substitutions;    s8=segment which is amino acid residue x7 to x8 of T1 and having 1-10 conservative amino acid substitutions.    EXAMPLE - No suitable example given.