Heme oxygenase from Leptospira interrogans is an important virulence factor. During catalysis, redox equivalents are provided to this enzyme by the plastidic-type ferredoxin-NADP+ reductase also found in L. interrogans. This process may have evolved to aid this bacterial pathogen to obtain heme-iron from their host and enable successful colonization. Herein we report the crystal structure of th...

Hemin treatment of the Philadelphia chromosome positive leukemia cell line, K562, accentuates a number of erythroid phenotypic characteristics. The nature of this hemin effect was investigated by examining heme production and heme biosynthetic and catabolic enzyme activity in untreated and 0.05 mM hemin-treated cells. Activities of -aminolevulinic acid synthetase (ALAS). the rate limiting heme ...

The seminal discovery of nitric oxide (NO) in the 1980s unraveled the novel concept that an endogenous production of a gaseous substance such as NO can impart diverse and critical functional effects on a wide spectrum of biological and pathological processes. Intense investigations in the chemistry and biology of NO have led to numerous fruitful discoveries, enhancing our understanding of many ...

The heme oxygenase (HO) system has received significant attention in recent years as a possible novel target for antihypertensive therapy. HO is the rate limiting enzyme in the metabolism of heme releasing bioactive molecules carbon monoxide (CO) and bilirubin each with beneficial cardiovascular actions. Induction of HO-1 has been demonstrated to lower blood pressure in several animal models of...

Earlier observations indicate that free heme is selectively toxic to cells lacking heme oxygenase-1 (HO-1) but how this enzyme prevents heme toxicity remains unexplained. Here, using A549 (human lung cancer) and immortalized human bronchial epithelial cells incubated with exogenous heme, we find knock-down of HO-1 using siRNA does promote the accumulation of cell-associated heme and heme-induce...

Heme is ferrous protoporphyrin-IX that is the prosthetic group of hemoproteins, such as hemoglobin, myoglobin and cytochromes that are of vital importance. In contrast, “free heme”, a protein-unbound heme, that is either just synthesized but yet not incorporated into hemoproteins, or that is released from hemoprotein under oxidative conditions, is highly toxic, since it catalyzes the production...

Utilization of heme by bacteria as a nutritional iron source involves the transport of exogenous heme, followed by cleavage of the heme macrocycle to release iron. Bradyrhizobium japonicum can use heme as an iron source, but no heme-degrading oxygenase has been described. Here, bioinformatics analyses of the B. japonicum genome identified two paralogous genes renamed hmuQ (bll7075) and hmuD (bl...