Introduction
Enzymes of the ammonia-lyase family, such as histidine ammonia lyase (HAL) and PAL, catalyze the deamination of amino acids (Poppe and Rétey, 2005). PAL (EC 4.3.1.24) activity has been demonstrated in plants, fungi, yeasts, and a number of microbial species including cyanobacteria, Photorhabdus luminescens, Sorangium cellulosum, and streptomyces (Fritz et al., 1976; Hanson and Havir, 1979; Williams et al., 2005; Hyun et al., 2011; Babaoǧlu Aydaş et al., 2013; Cui et al., 2013, 2014). PAL is the first enzyme in the phenylpropanoid sequence, a secondary metabolic pathway, in plants; this pathway is involved in the synthesis of important compounds including coumarins (have antimicrobial properties), lignins (used for structural support) and flavonoids (colorful component of many flowers; Koukol and Conn, 1961). PAL has a catabolic role in fungi, allowing the microbe to use L-Phe/L-Tyr as the sole source of carbon and nitrogen; in bacteria, the enzyme is involved in the synthesis of secondary metabolites (Hyun et al., 2011; Cui et al., 2014). PAL has not been found to date in animal tissues, including humans.
Phenylalanine ammonia lyase from different species including Rhodotorula glutinis yeast shows activity toward a broad range of phenylalanine analogs (MacDonald and D’Cunha, 2007). PAL catalyzes the transformation of L-Phe to t-CA and ammonia (Koukol and Conn, 1961). PAL has also been shown to accept L-PM as the substrate (D’Cunha et al., 1994). In addition, PAL reverse reactions for the synthesis of L-Phe from t-CA and L-PM from t-CM have been successfully demonstrated (Yamada et al., 1981; Evans et al., 1987a; D’Cunha et al., 1994). The enzyme is shown to have specificity for L-Tyr, that is, PAL can produce p-HCA by deamination of tyrosine (Neish, 1961). PAL enzymes that demonstrate specificity for L-Tyr are referred to as tyrosine ammonia lyases (TAL; EC 4.3.1.25); and the enzymes that show dual specificity toward L-Phe and L-Tyr are called PTAL (EC 4.3.1.26; Neish, 1961; Xue et al., 2007a).
The present study is an extension of the earlier work on PAL/PTAL catalyzed synthesis of important molecules and their applications (Neish, 1961; Yamada et al., 1981; Evans et al., 1987a; D’Cunha et al., 1994; Burchard et al., 2000; Solecka and Kacperska, 2003; Bouzid et al., 2006; Xue et al., 2007a,b; Dogbo et al., 2012) with the main objective being testing the efficacy of using R. glutinis PTAL in the biotransformation of L-TM to the methyl ester of p-HCAM according to the reaction shown in Figure 1A.
There are a number of reports on the synthesis cinnamic acid/ coumaric acid derivatives including the synthesis of p-HCAM (Venkateswarlu et al., 2006; Stankova et al., 2009; Khatkar et al., 2014). However, the procedures for p-HCAM formation employed lengthy and time-consuming multi-step methods with resultant low yields. There is therefore a need to develop a simple and rapid procedure for the production of p-HCAM, which has recently been shown to exhibit antimicrobial, antiviral and antioxidant activity (Proestos et al., 2006; Venkateswarlu et al., 2006; Stankova et al., 2009; Terpinc et al., 2011; Chochkova et al., 2013; McCarthy et al., 2013; Khatkar et al., 2014).
We have successfully demonstrated the direct one-step PTAL catalyzed synthesis of p-HCAM and confirmed that it shows antibacterial activity against several pathogenic bacteria. Derivatives of p-HCA, such as ferulic acid, have important roles in plants (Burchard et al., 2000), health and pharmaceutical applications (Burchard et al., 2000; Solecka and Kacperska, 2003), and food industry (Bouzid et al., 2006). Therefore, in addition to using p-HCAM as an antibacterial agent (perhaps as a topical treatment agent or disinfectant), we also intend testing its potential application as a food additive (inclusion in canned foods to prevent microbial contamination).
Hoặc