Effect of Laser and LED on Enzymatic Production of Ceramide Hongyu Zhang* 1 , Long Zhang 2 , Peter Tidemand-Lichtenberg 3 , Preben Buchhave 4 , Xuebing Xu 5 and Yingxin Li* 6,7 1 Shanxi Province Tumor Hospital, Taiyuan, Shanxi Province, China 2 Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Konges Lyngby, Denmark 3 DTU Fotonik, Technical University of Denmark, Roskilde, Denmark 4 Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark 5 Department of Molecular Biology, University of Aarhus, Aarhus C, Denmark 6 Laser Medicine Laboratory, Department of Biomedical Engineering, Tianjin Medical University, Tianjin, China 7 Institute of Biomedical Engineering, Chinese Academy of Medical Science—Peking Union Medical College, Tianjin, China Received 20 June 2010, accepted 16 September 2010, DOI: 10.1111/j.1751-1097.2010.00820.x ABSTRACT An enzyme (Phospholipase C Type I from Clostridium perfrin- gens) was exposed to 0–810 J cm )2 of energy using laser light at wavelengths 808, 532, 1064 and 1342 nm and two LED light sources at wavelengths 810 and 640 nm. Enzyme responses were evaluated by measuring ceramide concentration using high performance thin-layer chromatography (HPTLC) at 0.5, 1, 2, 3, 4, 6, 17, 24 h after irradiation. The duration of effect was evaluated from the experimental data. The results show that enzyme activity can be increased by using both laser and LED sources whose wavelength is located within a certain range. The effect depends on the energy and wavelength of the light. The increase in enzyme activity continued for about 4h after irradiation. This study shows that the duration of irradiation should be included as one of the main laser parameters when reporting on the effects of laser irradiation on enzymes. We also find that laser sources and LED sources have the same effect on enzyme activity if the wavelength and absorbed energy are equal. INTRODUCTION Laser radiation has been comprehensively explored in the context of cell diagnostics, clinical therapy, and microbiolog- ical studies (1,2). Laser technology has also been widely used to treat various skin diseases, neonatal jaundice (hyperbiliru- binemia) and cancer (3,4). The field of enzyme application has developed at a fast pace in the last few decades. The number of enzyme-based products is on the rise, having increasingly important roles in food, environmental, pharmaceutical and cosmetic industry applications. Consequently, the application of laser technology in enzymology and biocatalysis has emerged as an interesting topic. If laser irradiation within a certain range of intensity and frequency has a positive effect on enzymatic reactions, then laser technology can be used to increase the reaction rate or yield in many enzyme applica- tions. In terms of biological research, information on the effects of lasers on specific enzymatic reactions could also improve our understanding of their effects on entire biological systems. Unfortunately, only a limited number of publications have described the effects of lasers on specific enzymatic reactions. Satoshi et al. showed that thermal treatment using a 1547 nm laser (30–300 mW, spot size 50 lm, pulse duration 1 ns, exposure time 60 s) had a fatal influence on enzyme activity, while a femtosecond laser (0.4 mW, spot size 5 lm, pulse duration 200 fs, exposure time 1–10 s) and a pulsed UV laser (0.3 mW, spot size 25 lm, pulse duration 1 ns, exposure time 60 s) did not affect the protein integrity (5). Chen et al. also studied the effect of ultraviolet laser power on the enzyme activity of lactate dehydrogenase (LDH). In that study, LDH from bovine heart was exposed to 3.6–18 kJ m )2 of UV radiation in the 300 nm wavelength region and the degree of inactivity was found to be proportional to the amount of ultraviolet radiation power (6). However, the mechanism of these effects remains unclear. Ceramide (Fig. 1A) is the crucial intermediate in the metabolism of all complex sphingolipids. Because of its major role in maintaining the water-retaining properties of the epidermis, ceramide has great commercial potential in cos- metic and pharmaceutical industries for use in hair and skin care products (7,8). However, chemical synthesis of ceramide is a costly and time-consuming process (9). Therefore, the development of alternative cost-efficient and high yield pro- duction methods is of great interest. Sphingomyelin (SM) is a ubiquitous component of animal cell membranes and is one of the major phospholipids in bovine milk. In SM, the ceramide part of the molecule is bound by a phosphodiester bridge to a choline moiety (Fig. 1B). Systematic investigation and optimi- zation have been conducted for the enzymatic production of ceramide from SM hydrolysis (10) and phospholipase C (PLC) from Clostridium perfringens, and high activity towards the hydrolysis reaction has been demonstrated. In the present study, the aim is to evaluate the potential of laser technology in enzymatic reactions, specifically the *Corresponding author emails: hongyushen2008@yahoo.com.cn (Hongyu Zhang); yingxinli@tijmu.edu.cn (Yingxin Li) Ó 2010 Tianjin Medical University Photochemistry and Photobiology Ó 2010 The American Society of Photobiology 0031-8655/11 Photochemistry and Photobiology, 2011, 87: 131–136 131