Abstract: An enzyme referred to as carbon monoxidase and referred to hereinafter as CMase is present in red blood cells and in various bacteria and plants, including algae and fungi. The enzyme is effective for the conversion of carbon monoxide in a gas stream. Where the conversion is the step of oxidizing CO to CO.sub.2, the enzyme can be used for detection of CO. The procedure lends itself to quantitative determination of CO in a gas stream. The production of CMase can be accelerated by growing bacterial cultures or plants in an atmosphere containing an increased concentration of carbon monoxide. Increasing the concentration of oxygen simultaneously is also beneficial to the process.A filter medium including CMase can substantially decrease the concentration of carbon monoxide in a gas stream, the gas stream of particular interest being tobacco smoke. Combining the CMase in a filter with copounds which bind CO reversibly presents advantages.

Abstract: Ferrous hemoglobin in a form suitable for absorption of carbon monoxide is produced from a hemoglobin solution, buffered to prevent denaturation of the hemoglobin, and containing an effective reductant. The quantity of reductant present is at least sufficient to counteract the effect of oxygen in such air as comes in contact with the hemoglobin. Enzymatic digestion products of hemoglobin, also active for the absorption of carbon monoxide are produced by controlled decomposition of hemoglobin. These products are lower in equivalent weight than is hemoglobin so that the quantity needed for absorbing a given quantity of carbon monoxide is reduced.

Abstract: The quantity of carbon monoxide removed from a gas stream by a filter containing hemoglobin is greatly enhanced in quantity when the hemoglobin is accompanied by another factor present in blood. The quantity of carbon monoxide removable from a gas stream by hemoglobin depends upon the equivalent weight of the hemoglobin. However, in the presence of the additional factor, the quantity of carbon monoxide removed is substantially greater than can be accounted for by the stoichiometry of the hemoglobin alone.