_applied_  
_sciences_  
_Editorial_  
Enzyme Catalysis: Advances, Techniques, and Outlooks  
**[PERSON]**  
Division of Plant Biosciences, School of Applied Biosciences, College of Agriculture and Life Science,  
Kyungpook National University, Daegu 41566, Korea; [EMAIL_ADDRESS]; Tel. : +82-53-950-6654  
Biocatalysis using enzymes is a powerful strategy that can be employed in a variety of industries for the production of biofuel, biochemicals, pharmaceuticals, and foods, etc. [1]. Compared with the chemical method, enzyme catalyst is considered as an eco-friendly and more selective tool, facilitating a sustainable and circular economy. Enzymes possessing high catalytic efficiency, stability to harsh conditions (i.e., heat, extreme pH, and high salinity), and desired substrate specificity are considered to be process-compatible. To discover such robust enzymes, various technologies of bioinformatics, machine learning, protein engineering, and high-throughput screening (HTS) have been developed [2]. With the aid of those cutting edge technologies, it is more readily achievable to discover and develop novel and superior enzymes. Noteworthy, [PERSON]'s award of the Nobel Prize in 2018 for protein engineering facilitates the scaled-up applications of enzyme in industries. This Special Issue \"Enzyme Catalysis: Advances, Techniques, and Outlooks\" aimed to contribute to the advancement of related fields by covering broad subjects and technological developments on industrially relevant enzymes, such as sugar isomerase (i.e., glucose/ fucose isomerase, lysozyme, protease, and cytochrome P450. Under this Special Issue, a total of six papers were published, comprising five original research papers and one review paper. Cytochrome P450 is considered as industrially useful biocatalyst due to its versatility [3]. [PERSON] et al. reported an efficient enzymatic strategy using bacterial CYP1O2A1 peroxidase for the synthesis of 4-OH atorvastatin from atorvastatin, which is the key human metabolite having a beneficial effect on cardiovascular disease and hyperlipidemia [4]. Specifically, a superior mutant of CYP102A1 was obtained with a catalytic efficiency of 1.8 min\({}^{-1}\) with an aid of HTS and enzyme characterization. This approach was conducted in the presence of hydrogen peroxide but without NADPH, which was further discussed on its advantage over NADPH-requiring monooxygenase. The Michaelis-Menten equation is routinely used for the investigation of enzyme kinetics. However, when the reaction product acts as the inhibitor, this conventional model does not necessarily reflect the enzyme's actual behaviors, causing a misinterpretation. For reliability, [PERSON] et al. developed a robust methodology based on an integrated Michaelis-Menten equation (IMME) [5], which could be helpful for the investigation of enzymes such as the well-known \(\beta\)-glucosidase, often encountering end-product inhibition (i.e., glucose) [6]. [PERSON] et al. developed a more efficient detergent than commercial ones by preparing for in-house blends composed of different proteases (i.e., alkaline protease, keratinase, and trypsin) combined with detergent additives including surfactants, anti-redeposition agents, and water-softening agents [7]. During the process, various approaches, such as whiteness determination, microscope scanning, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to assess the cleaning efficiency. Sugar isomerase is a class of enzymes that mediate the interconversion of sugar isomers in a reversible manner. With its broad substrate scope, this enzyme has wide applications in food/beverage, pharmaceutical/medicinal, and beauty industries [8]. The well-recognized glucose isomerase (GI), which is involved in catalyzing the reaction between d-glucose and d-fructose, and d-xylose and d-xylulose has already been commercially available for the production of high-fructose corn syrup.