Biology subjects

Huang, X. N.

Publications and source records attributed to Huang, X. N..

2 recordsLinked to original sources

bioRxiv2026

Immobilized neuroglobin scavenges carbon monoxide from circulating carboxyhemoglobin

Carbon monoxide (CO) poisoning is responsible for around 50,000 emergency department visits per year in the U.S. alone. With the present standard of care, persistent neurological sequelae occur in [~]30-40% of severe CO poisoning cases. Currently, there is no available targeted molecular antidote for CO poisoning. In previous work, we have developed an antidotal therapy for CO poisoning based on an engineered hemeprotein, human neuroglobin (Ngb-H64Q-CCC). Intravenous infusion of Ngb-H64Q-CCC removes CO from the circulating red blood cells and improves survival in a lethal CO-poisoning mouse model. However, the infusion of heme-containing proteins has inherent heme toxicity risks that may limit the dose that can be used safely without liver or kidney toxicity. In order to overcome these problems, we have investigated the development of immobilized Ngb in a solid matrix. This approach allows for the development of a CO removal system using an extracorporeal blood circulating system coupled with a stationary matrix with immobilized Ngb-H64Q-CCC. Such system avoids drug infusion and possible organ injury, allows for antidote recycling, and provides advantages for storage and handling of the antidote. By assessing the efficacy of Ngb-H64Q-CCC immobilized through different linkage strategies, we have identified N-hydroxysuccinimide agarose resin as a viable stationary phase. The immobilized protein shows preserved heme redox activity, can be chemically reduced/oxidized for activation/CO release purposes, and retains its CO removal capacity after successive regeneration cycles. We expect that this novel approach will advance the development of new scavenger-based therapies for CO poisoning.

bioengineering↗

bioRxiv2025

Cytochrome b5 reductase 4 efficiently reduces Neuroglobin and Cytoglobin

Cytoglobin and Neuroglobin are heme-containing proteins expressed in most vertebrates, including mammals, with still not completely defined physiological roles. Most of the putative functions of cytoglobin/neuroglobin, such as oxygen binding or nitric oxide dioxygenation, rely on the heme iron being in the ferrous (Fe2+) oxidation state. Therefore, it is very possible that reducing systems are active in the cell to maintain both proteins in the ferrous state. We have previously shown that the cytochrome b5 reductase isoform 3/ cytochrome b5 system, the canonical reductase of hemoglobin and myoglobin, can reduce cytoglobin at very fast rates, consistent with a possible physiological role. However this reducing system is unable to reduce neuroglobin, which to date lacks a validated, physiologically feasible reducing system. Here we have studied the interaction of cytochrome b5 reductase isoform 4 with cytoglobin and neuroglobin and found that cytochrome b5 reductase 4 can reduce cytoglobin at rates comparable to those observed with cytochrome b5 reductase 3/ cytochrome b5. Remarkably, it can also reduce neuroglobin efficiently. Studying different surface mutations of cytoglobin and neuroglobin we note that some cytoglobin mutations, in particular R84E and K116E decrease reduction rates by more than 10-fold, whereas surface mutations in neuroglobin that were shown to impair the interaction of neuroglobin with cytochrome c (E60K/D73K/E87K) show little effect on the reduction rates. We conclude that cytochrome b5 reductase 4 can supplement cytochrome b5 reductase 3/ cytochrome b5 roles for cytoglobin reduction in vivo and is a strong candidate for a physiological role as neuroglobin reductase.

biochemistry↗