Biochemical Characterization of Kluyveromyces lactis Adenine Deaminase and Guanine Deaminase and Their Potential Application in Lowering Purine Content in Beer.

Durga Mahor,Gandham S Prasad

doi:10.3389/fbioe.2018.00180

Durga Mahor, Gandham S Prasad

Open Access

https://doi.org/10.3389/fbioe.2018.00180

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Abstract

Excess amounts of uric acid in humans leads to hyperuricemia, which is a biochemical precursor of gout and is also associated with various other disorders. Gout is termed as crystallization of uric acid, predominantly within joints. The burden of hyperuricemia and gout has increased worldwide due to lifestyle changes, obesity, and consumption of purine-rich foods, fructose-containing drinks, and alcoholic beverages. Some of the therapies available to cure gout are associated with unwanted side-effects and antigenicity. We propose an attractive and safe strategy to reduce purine content in beverages using enzymatic application of purine degrading enzymes such as adenine deaminase (ADA) and guanine deaminase (GDA) that convert adenine and guanine into hypoxanthine and xanthine, respectively. We cloned, expressed, purified, and biochemically characterized both adenine deaminase (ADA) and guanine deaminase (GDA) enzymes that play important roles in the purine degradation pathway of Kluyveromyces lactis, and demonstrate their application in lowering purine content in a beverage. The popular beverage beer has been selected as an experimental sample as it confers higher risks of hyperuricemia and gout. Quantification of purine content in 16 different beers from the Indian market showed varying concentrations of different purines. Enzymatic treatment of beer samples with ADA and GDA showed a reduction of adenine and guanine content, respectively. These enzymes in combination with other purine degrading enzymes showed marked reduction in purine content in beer samples. Both enzymes can work at 5.0–8.0 pH range and retain >50% activity at 40°C, making them good candidates for industrial applications.

Highlights

Hyperuricemia, an elevated level of uric acid, is an independent risk factor for hypertension, metabolic, and cardiovascular disorders
We mainly focused on adenine deaminase and guanine deaminase enzymes of the purine degradation pathway of K. lactis and their application in lowering purine content in beverages
We report the biochemical characterization of KlacADA and KlacGDA and their application in lowering purine content in beer

Summary

Introduction

Hyperuricemia, an elevated level of uric acid, is an independent risk factor for hypertension, metabolic, and cardiovascular disorders It causes painful arthritis known as gout (Chen et al, 2007; Kuwabara, 2016) and it is the most common inflammatory arthritis, affecting 1–2% of the adult population (Richette and Bardin, 2010). One of the strategies to make this therapy safe and attractive is to produce the foods and beverages that are low in purine content through the enzymatic application (Trautwein-Schult et al, 2014; Jankowska et al, 2015; Mahor et al, 2016) This gives the patients an option to choose a wide variety of low purine content foods and beverages without any risk of hyperuricemia and gout

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