TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Variant: In the isolated cellulase variant, the substitution at one or more positions comprises removal of one or more positive charges, where the removal of one or more positive charges comprises a replacement of a lysine or an arginine with a neutral amino acid. Also, the substitution at one or more positions comprises addition of one or more negative charges, where the addition of one or more negative charges comprises a replacement of a neutral amino acid with a negatively charged amino acid. Likewise, the substitution at one or more positions comprises removal of one or more positive charges and addition of one or more negative charges, where the removal of one or more positive charges and addition of one or more negative charges comprises a placement of a lysine or an arginine with a negatively charged amino acid. The substitution at one or more positions comprises one or more of Lys129Glu, Lys157Glu, Lys194Glu, Lys288Glu, Lys327Glu, Lys356Glu, Arg63Gln, Arg77Gln, Arg153Gln, Arg203gln, Arg294Gln, Arg378Gln, Asn161Asp, Asn197Asp, Asn237Asp, Asn247Asp, Asn254Asp, Asn285Asp, Asn289Asp, Asn339Asp, Asn344Asp, Asn382Asp, Gln147Glu, Gln204Glu, Gln239Glu, and Gln281Glu, where the positions are numbered by correspondence with the amino acid sequence of the reference CBH2 set forth as SEQ ID NO: 3. Moreover, the variant comprises a further substitution at one or more further positions selected from 146, 151, 189, 208, 211, 244, 277 and 405, where the further positions are numbered by correspondence with the amino acid sequence of the reference CBH2 set forth as SEQ ID NO: 3, where the substitution at one or more further positions comprises a replacement of aspartic acid or glutamic acid with a neutral amino acid. The further substitution at one or more further positions comprises one or more of Asp151Asn, Asp189Asn, Asp211Asn, Asp277Asn, Asp405Asn, Glu146Gln, Glu208Gln, and Glu244Gln, where the positions are numbered by correspondence with the amino acid sequence of the reference CBH2 set forth as SEQ ID NO: 3. The substitution at one or more positions is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 positions. The cellulase variant is derived from a parent cellulase selected from Hypocrea jecorina CBH2, Hypocrea koningii CBH2, Humicola insolens CBH2, Acremonium cellulolyticus CBH2, Agaricus bisporus CBH2, Fusarium osysporum EG, Phanerochaete chrysosporium CBH2, Talaromyces entersonii CBH2, Thermobifida fusca 6B/E3 CBH2, Thermobifida fusca 6A/E2 EG, and Cellulomonas fimi CenA EG. The cellulase variant is derived from a parent cellulase whose amino acid sequence is at least 75% identical to a member of SEQ ID NO: 3-13, sequences not defined here may be found at ftp://ftp.wipo.int/pub/published_pct_sequences/publication. The more negative net charge is a -1 or -2 in comparison to the reference CBH2. Alternatively, the cellulase variant, where the variant is the mature form having cellulase activity and comprising a chemical modification of a lysine residue to remove positive charge of the lysine residue, where the chemical modification comprises a treatment with a compound selected from succinic anhydride, acetoxysuccinic anhydride, maleic anhydride, tartaric anhydride, phthalic anhydride, trimetallitic anhydride, cis-aconitic anhydride, t-nitrophthalic anhydride, acetic anhydride, butyric anhydride, isobutyric anhydride, hexanoic anhydride, valeric anhydride, isovaleric anhydride, and pivalic anhydride. The cellulase variant is derived from a parent cellulase selected from a H. jecorina CBHI, H. jecorina CBHII, H. jecorina endoglucanase I, H. jecorina endoglucanase II, and H. jecorina beta-glucosidase. SPECIFIC SEQUENCES - Specifically claimed is CBH2 amino acid sequences comprising fully defined 447 amino acids (SEQ ID NO: 3) given in the specification.    EXAMPLE - No suitable example given.