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Cleavage of proalbumin peptides by furin reveals unexpected restrictions at the P 2 and P′ 1 sites
Author(s) -
Brennan Stephen O.,
Nakayam Kazuhisa
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00511-7
Subject(s) - furin , cleavage (geology) , peptide , chemistry , protein precursor , stereochemistry , biochemistry , enzyme , biology , paleontology , fracture (geology)
Proalbumin is the principal substrate of the in situ hepatic convertase. Here we investigated the specificity of furin using synthetic peptides based on the N‐terminal sequence of human proalbumin. The propeptide was rapidly cleaved from the normal ((−6)RGVFRR(−1)DAHKSEAVW(+9)) peptide but as expected, there was no cleavage of the proalbumin Lille analogue with a −2 His (−2H). Surprisingly, the effect of this substitution could not be corrected by introducing a −4 Arg (−4R−2H). In contrast, the peptide −4R−2A was an excellent substrate being cleaved five times faster than normal, indicaabting that His is not allowed as an P 2 residue. Replacement of the −4 Val by Glu supported the expected importance of a positive charge at P 4 as the cleavage rate dropped to 10% of normal after this substitution. The −6 Arg makes a small contribution to cleavage, its replacement by Ala decreased the cleavage rate to 60% of normal. The Lys‐Arg propeptide was almost as good a substrate as the normal Arg‐Arg peptide, but the introduction of a Lys at P′ 1 totally abolished processing. The exclusion of P′ 1 positive charges would be an important requirement for preventing aberrant cleavage in the middle of tetrabasic sequences.