EXPRESSION, RECONSTITUTION AND CHARACTERIZATION OF PROLIXIN-S AS A VASODILATOR - A SALIVARY-GLAND NITRIC-OXIDE-BINDING HEMOPROTEIN OF RHODNIUS-PROLIXUS
M. Yuda et al., EXPRESSION, RECONSTITUTION AND CHARACTERIZATION OF PROLIXIN-S AS A VASODILATOR - A SALIVARY-GLAND NITRIC-OXIDE-BINDING HEMOPROTEIN OF RHODNIUS-PROLIXUS, European journal of biochemistry, 249(1), 1997, pp. 337-342
Prolixin-S, an anticoagulant from the salivary gland of the blood-suck
ing insect Rhodnius prolixus is also one of the members of salivary gl
and hemoproteins. We produced recombinant protein using a baculovirus-
insect cell expression system, reconstituted the hemoprotein and made
some characterization of it as a nitric oxide carrier. The reconstitut
ed protein exhibited the absorption spectrum of a high-spin ferric hem
oprotein with a Soret absorption peak at 400 nm. By binding nitric oxi
de (NO-prolixin-S), the Soret band shifted from 400 nm to 420 nm and t
wo sharp bands (Q bands, at 535 nm and 565 nm) also appeared in the vi
sible region. In a bioassay with aortic smooth muscle, NO-prolixin-S s
howed strong relaxation activity in a dose-dependent manner, which dem
onstrated that prolixin-S really acts as an NO carrier. A Soret absorp
tion change also indicated that nitric oxide was gradually released un
der these conditions (pH 7.4 and 37 degrees C). However, at low temper
ature (20 degrees C) and/or low pH (pH 6), which mimic those in the in
sect's salivary glands, the releasing became very slow. These differen
t NO-binding properties would enable prolixin-S to reserve nitric oxid
e in the salivary glands and release it in the host's blood vessels.