NOVELTY - A polypeptide comprising a variant cellobiohydrolase 1 (CBH1) catalytic domain as compared to a reference CBH1 catalytic domain, comprising: (a) a substitution at the amino acid position corresponding to Arg268 of Trichoderma reesei CBH1 (Arg268 substitution); (b) a substitution at the amino acid position corresponding to Arg411 of T. reesei CBH1 (Arg411 substitution); or (c) both an Arg268 substitution and an Arg411 substitution, where substitution (a), (b) or (c) decreases product inhibition as compared to the reference CBH1 catalytic domain, is new.    USE - The polypeptide, composition and fermentation broth are useful for saccharifying biomass and for producing a fermentation product such as ethanol (all claimed) and used in cellulosic material processing such as pulp and paper, textiles and animal feeds.    ADVANTAGE - The new and improved variant CBH1 polypeptides have reduced product inhibition. The polypeptides have improved productivity that maintains their reaction rates during the course of a saccharification reaction.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a composition comprising a polypeptide above;    (2) a fermentation broth comprising a polypeptide above;    (3) a method for saccharifying biomass by treating biomass with a composition or with a fermentation broth abo9ve;    (4) a method for producing a fermentation product by (a) treating biomass with a composition or with a fermentation broth above, thus producing fermentable sugars; and (b) culturing a fermenting microorganism in the presence of the fermentable sugars produced in step (a) under fermentation conditions, thus producing a fermentation product;    (5) a nucleic acid comprising a nucleotide sequence encoding the polypeptide above;    (6) a vector comprising the nucleic acid of (5);    (7) a recombinant cell engineered to express the nucleic acid of (5);    (8) a host cell transformed with the vector of (6);    (9) a method of producing a polypeptide;    (10) a method for generating a product tolerant variant CBH1 polypeptide, by (a) modifying the nucleotide sequence of a CBH1-encoding nucleic acid so that the nucleic acid encodes a variant CBH1 polypeptide above; and (b) expressing the variant CBH1 polypeptide, thus generating a product tolerant variant CBH1 polypeptide; and    (11) a method for generating a nucleic acid that encodes a product tolerant variant CBH1 polypeptide, by modifying the nucleotide sequence of a CBH1-encoding nucleic acid so that the nucleic acid encodes a variant CBH1 polypeptide above, thus generating a nucleic acid that encodes a product tolerant variant CBH1 polypeptide.