6EAT

Crystallographic structure of the cyclic nonapeptide derived from the BTCI inhibitor bound to beta-trypsin in space group P 21 21 21.

Summary for 6EAT

• Entry DOI: 10.2210/pdb6eat/pdb
• Related: 2G81 3RU4 6E5M 6EAU 6EAV 6EAW 6EAX
• Descriptor: Cationic trypsin, 9MER-PEPTIDE, CALCIUM ION, ... (5 entities in total)
• Functional Keywords: inhibitor complex, btci, hydrolase, hydrolase-hydrolase inhibitor complex, hydrolase/hydrolase inhibitor
• Biological source: Bos taurus (Bovine); More
• Total number of polymer chains: 2
• Total formula weight: 25494.30

Authors

Fernandes, J.C.,Valadares, N.F.,Freitas, S.M.,Barbosa, J.A.R.G. (deposition date: 2018-08-03, release date: 2019-03-13, Last modification date: 2024-11-13)

Primary citation

Fernandes, J.P.C.,Mehdad, A.,Valadares, N.F.,Mourao, C.B.F.,Ventura, M.M.,Barbosa, J.A.R.G.,Freitas, S.M.
Crystallographic structure of a complex between trypsin and a nonapeptide derived from a Bowman-Birk inhibitor found in Vigna unguiculata seeds.
Arch. Biochem. Biophys., 665:79-86, 2019

PubMed Abstract: Natural inhibitors of proteases have been classified into different families, among them is the Bowman-Birk Inhibitor (BBI) family. Members of BBI have two structurally reactive loops that simultaneously inhibit trypsin and chymotrypsin. Here, we have investigated the binding of bovine trypsin by a cyclic nonapeptide, named PTRY9 (CTKSIPPQC), derived of the black-eyed pea trypsin/chymotrypsin inhibitor (BTCI) from Vigna unguiculata seeds. This peptide was synthetically produced with the disulfide bond restraining its conformation to mimic the reactive loop that inhibits trypsin. PTRY9 complexed to pancreatic bovine trypsin was crystallized in orthorhombic and trigonal space groups, P222 and P321, with maximum resolutions of 1.15 and 1.61 Å, respectively. The structures presented refinement parameters of R = 14.52 % and R = 15.59 %; R = 15.60 % and R = 18.78 %, and different surface area between the peptide and the enzyme of 1024 Å and 1070 Å, respectively. The binding site of the PTRY9 is similar to that found for BTCI as shown by a r.m.s.d. of 0.358 Å between the superimposed structures and the electrostatic complementary pattern at the enzyme-peptide interface. Additionally, enzyme inhibition assays show that the affinity of trypsin for PTRY9 is smaller than that for BTCI. In vitro assays revealed that, like BTCI, this synthetic peptide is not cytotoxic for normal mammary epithelial MCF-10A cells, but exerts cytotoxic effects on MDA.MB.231 invasive human breast cancer cells.

PubMed: 30817908
DOI: 10.1016/j.abb.2019.02.013

Experimental method

X-RAY DIFFRACTION (1.149 Å)