MP-4 Contributes to Snake Venom Neutralization by Mucuna pruriens Seeds through an Indirect Antibody-mediated Mechanism.
A.Kumar,
C.Gupta,
D.T.Nair,
D.M.Salunke.
ABSTRACT
Mortality due to snakebite is a serious public health problem, and available
therapeutics are known to induce debilitating side effects. Traditional medicine
suggests that seeds of Mucuna pruriens can provide protection against the
effects of snakebite. Our aim is to identify the protein(s) that may be
important for snake venom neutralization and elucidate its mechanism of action.
To this end, we have identified and purified a protein from M. pruriens, which
we have named MP-4. The full-length polypeptide sequence of MP-4 was obtained
through N-terminal sequencing of peptide fragments. Sequence analysis suggested
that the protein may belong to the Kunitz-type protease inhibitor family and
therefore may potentially neutralize the proteases present in snake venom. Using
various structural and biochemical tools coupled with in vivo assays, we are
able to show that MP-4 does not afford direct protection against snake venom
because it is actually a poor inhibitor of serine proteases. Further experiments
showed that antibodies generated against MP-4 cross-react with the whole venom
and provide protection to mice against Echis carinatus snake venom. This study
shows that the MP-4 contributes significantly to the snake venom neutralization
activity of M. pruriens seeds through an indirect antibody-mediated mechanism.