Folding of bovine pancreatic trypsin inhibitor (BPTI) variants in which almost half the residues are alanine.


Recent studies indicate that a fraction of the information contained in an amino acid sequence may be sufficient for specifying a native protein structure. An earlier alanine-scanning experiment conducted on bovine pancreatic trypsin inhibitor (BPTI; 58 residues) suggested that if cumulative mutations have additive effects on protein stability, a native protein structure could be built from BPTI sequences that contained many alanine residues distributed throughout the protein. To test this hypothesis, we designed and produced six BPTI mutants containing from 21 to 29 alanine residues. We found that the melting temperature of mutants containing up to 27 alanine residues (48 % of the total number of residues) could be predicted quite well by the sum of the change in melting temperature for the single mutations. Additionally, these same mutants folded into a native-like structure, as judged by their cooperative thermal denaturation curves and heteronuclear multiple quantum correlation (HMQC) NMR spectra. A BPTI mutant containing 22 alanine residues was further shown by 2D and 3D-NMR to fold into a structure very similar to that of native BPTI, and to be a functional trypsin inhibitor. These results provide insight into the extent to which native protein structure and function can be achieved with a highly simplified amino acid sequence. Study holds ProTherm entries: 8087, 8088, 8089, 8090, 8091 Extra Details: protein structure; alanine-scanning; information degeneracy; NMR

Submission Details

ID: segUq97z

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:35 p.m.

Version: 1

Publication Details
Kuroda Y;Kim PS,J. Mol. Biol. (2000) Folding of bovine pancreatic trypsin inhibitor (BPTI) variants in which almost half the residues are alanine. PMID:10772865
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Pancreatic trypsin inhibitor P00974 BPT1_BOVIN
91.0 Pancreatic trypsin inhibitor P04815 BPT2_BOVIN
91.4 Pancreatic trypsin inhibitor P00975 IBPS_BOVIN