Rhodnius prolixus

The Nitric Oxide-Releasing Heme Proteins from the Saliva of the Blood-Sucking Insect Rhodnius prolixus F. Ann Walker and William R. Montfort... 

Rhodniin 11 too Rhodnius prolixus Binds to and inhibits thrombin... 

THE NITRIC OXIDE-RELEASING HEME PROTEINS FROM THE SALIVA OF THE BLOOD-SUCKING INSECT Rhodnius prolixus... 

C. Early Work on the Nitrophorins from Rhodnius prolixus... 

NO-RELEASING HEME PROTEINS FROM Rhodnius prolixus SALIVA... 

Fig. 1. Nitric oxide (NO) synthesis by nitric oxide synthase (NOS) (upper left), NO reaction with soluble guanylate cyclase (sGC) (middle), and formation of cyclic GMP, which causes tissue-specific signaling (right). The roles of the salivary nitrophorins from Rhodnius prolixus in storing and releasing NO and binding histamine are included (lower left).

Fig. 2. Simplified illustration of the steps in blood coagulation inhibited by the salivary proteins of Rhodnius prolixus. The inhibited steps are indicated with crossed arrows. SAPLl-3 are also called RPAIl-3.

Fig. 9. The continuous wave EPR spectrum of recombinant Rhodnius prolixus NPl-histamine at a microwave frequency of 9.338 GHz (trace 1) and field-sweep ESE spectra at 8.706 GHz (trace 2), 3.744 GHz (trace 3), 3.065 GHz (trace 4). Dashed arrows show the changes in magnetic fields corresponding to principalg -values at the different microwave frequencies. Inset trace 1, the primary ESE decay recorded at 8.706 GHz, Bo = 213 mT (the low-field turning point in the field-sweep ESE spectrum shown by trace 2 in the main panel). Inset trace 2, the primary ESE decay recorded at 3.065 GHz, Bo = 140.8 mT (the high-field turning point in the field-sweep ESE spectrum shown by trace 4 in the main panel). Reproduced with permission from Ref. (89).

Fig. 23. The dissociation constants and redox stability of the NO and histamine complexes of the nitrophorins from the saliva of Rhodnius prolixus, and how they aid the insect in obtaining a sufficient blood meal. Modified from Ref (.31).

Montfort, W. R. Weichsel, A. Andersen, J. F. Nitrophorins and Related Antihemostatic Lipocahns from Rhodnius prolixus and Other Blood-Sucking Arthropods. Biochim. Biophys. Acta. 2000, in press. 

Since the primary structure of a peptide determines the global fold of any protein, the amino acid sequence of a heme protein not only provides the ligands, but also establishes the heme environmental factors such as solvent and ion accessibility and local dielectric. The prevalent secondary structure element found in heme protein architectures is the a-helix however, it should be noted that p-sheet heme proteins are also known, such as the nitrophorin from Rhodnius prolixus (71) and flavocytochrome cellobiose dehydrogenase from Phanerochaete chrys-osporium (72). However, for the purpose of this review, we focus on the structures of cytochromes 6562 (73) and c (74) shown in Fig. 2, which are four-a-helix bundle protein architectures and lend themselves as resource structures for the development of de novo designs. 

---