Biliverdin reductase, catalytic. Members of this family adopt a structure consisting of four alpha helices and six beta sheets, in an alpha-beta-alpha-alpha-alpha-beta-beta-beta-beta-beta arrangement. They contain a catalytic active site, capable of reducing the gamma-methene bridge of the open tetrapyrrole, biliverdin IX alpha, to bilirubin with the concomitant oxidation of a NADH or NADPH cofactor.