Horseradish and soybean peroxidases (HRP and SBP, respectively) are useful biotechnological tools. HRP is often termed the classical plant heme peroxidase, and although it has been studied for decades our understanding has deepened since its cloning and subsequent expression, which has enabled numerous mutational and protein engineering studies. SBP, however, has been neglected until recently; despite offering a real alternative to HRP that actually outperforms it in terms of stability. SBP is now used in numerous biotechnological applications, including biosensors. Review of both is timely. This article summarises and discusses the main insights into the structure and mechanism of HRP, with special emphasis on HRP mutagenesis, and outlines its use in a variety of applications. It also reviews current knowledge and applications to date of SBP, particularly biosensors. The final paragraphs speculate on the future of plant heme-based peroxidases, with probable trends outlined and explored
