title: Complementation of intramolecular interactions for structural-functional stability of plant serine proteinase inhibitors.
abstract: BACKGROUND
  Plant protease inhibitors (PIs) constitute a diverse group of proteins capable of inhibiting proteases. Among PIs, serine PIs (SPIs) display stability and conformational restrictions of the reactive site loop by virtue of their compact size, and by the presence of disulfide bonds, hydrogen bonds, and other weak interactions.
  
  
  METHODS
  The significance of various intramolecular interactions contributing to protein folding mechanism and their role in overall stability and activity of SPIs is discussed here. Furthermore, we have reviewed the effect of variation or manipulation of these interactions on the activity/stability of SPIs.
  
  
  CONCLUSIONS
  The selective gain or loss of disulfide bond(s) in SPIs can be associated with their functional differentiation, which is likely to be compensated by non-covalent interactions (hydrogen bonding or electrostatic interactions). Thus, these intramolecular interactions are collectively responsible for the functional activity of SPIs, through the maintenance of scaffold framework, conformational rigidity and shape complementarities of reactive site loop.
  
  
  CONCLUSIONS
  Structural insight of these interactions will provide an in-depth understanding of kinetic and thermodynamic parameters involved in the folding and stability mechanisms of SPIs. These features can be explored for engineering canonical SPIs for optimizing their overall stability and functionality for various applications.
authors.affiliation: Plant Molecular Biology Unit, Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008 (MS), India.
authors.forename: Rakesh S
authors.initials: RS
authors.lastname: Joshi
authors.forename: Manasi
authors.initials: M
authors.lastname: Mishra
authors.forename: C G
authors.initials: CG
authors.lastname: Suresh
authors.forename: Vidya S
authors.initials: VS
authors.lastname: Gupta
authors.forename: Ashok P
authors.initials: AP
authors.lastname: Giri
mesh_terms: D020134:Catalytic Domain; D010940:Plant Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D017510:Protein Folding; D012694:Serine / Q000378:metabolism*; D057057:Serine Proteases / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D010940:Plant Proteins; D015842:Serine Proteinase Inhibitors; D012694:Serine; D057057:Serine Proteases
keywords: Disulfide bond; Hydrogen bonding; Intramolecular weak interaction; MEROPS Database ID; MI; PI; Protease; Proteinase inhibitor; RSL; Reactive site loop; SPI; Serine proteinase inhibitor