Regulation of the Fasciola hepatica newly excysted juvenile cathepsin L3 (FhCL3) by its propeptide: a proposed ‘clamp-like’ mechanism of binding and inhibition

Table 1 FhCL3 propeptide amino acid residues predicted to interact with the propeptide binding loop (PBL) and substrate binding site of the mature F. hepatica and human cathepsin L and cathepsin K peptidases

ppFhCL3	Residues within the mature cathepsin
ppFhCL3	FhCL3	FhCL2	FhCL1	HsCL	HsCK
Tyr⁴⁶	Asp²²⁸ ^aPhe²³⁷	Asp²⁴⁸	Asp²⁴⁸	Ser²⁵⁵	Ser²⁵⁵
Lys⁴⁷	^bSer²³⁴ ^cGlu²³³	Ser²⁵⁴	Ser²⁵⁴	Glu²⁶¹ Lys²⁶⁰	Lys²⁶¹ Ser²⁶⁰
Leu^{66 *}	Ala²²⁵	Ala²⁴⁵	Val²⁴⁵	Gly²⁵²	Ser²⁵²
Glu^{68 *}	Thr²⁴⁸	Thr²⁶⁸	Asn²⁶⁸	Asp²⁷⁵	Asn²⁷⁵

* Residues interacting within the substrate binding site of the cathepsin peptidase
a, π-π interaction; b, hydrogen bonds; c, salt bridge formed between residues of the ppFhCL3 and the mature domain of FhCL3

ISSN: 2661-8850