A novel enzymatic approach in the production of food with low purine content using Arxula adeninivorans endogenous and recombinant purine degradative enzymes

Figures & data

Figure 1. Schema of proposed purine degradation pathway in A. adeninivorans. The presence of OHCU decarboxylase has not been confirmed yet.

Figure 2. The influence of nitrogen source on transcript accumulation of (A) AADA, (B) AXOR, (C) AUAY (D) AGDA, (E) AUOR. The A. adeninivorans cells were cultivated in yeast minimal medium with glucose (1%) as carbon source and various purines as nitrogen sources at different concentrations for 24 h. The transcript was analyzed by qPCR. Used markers: (□) adenine, (▴) hypoxanthine, (○) uric acid.

Table 1. Comparison of the properties of purified recombinant adenine deaminase (Aada6hp), guanine deaminase (Agda6hp), urate oxidase (Auor6hp) and wild-type xanthine oxidoreductase (Axorp)

Property	Aada6hp	Agda6hp	Axorp	Auor6hp
pH optimum	6.5	6.5	8.5	9.5
pH range^*	5.5–7.5	6.0–8.0	7.5–9.5	8.0–10.0
pH stability^*	7.5–8.5	6.5–8.0	8.0–10.5	8.0–10.0
Temperature optimum	40°C	55°C	43°C	35°C
Temperature range^*	34–46°C	40–60°C	35–50°C	30–45°C
Temperature stability/1h^*	30°C	30°C	30°C	50°C

* Temperature, pH range and stability were defined as the temperature and pH at which over 80% of the initial activity was retained. pH stability was measured after incubation for: 24 h for Aada6hp, 4 h for Axorp, 1 h for Auor6hp and Agda6hp.

Figure 3. Production of food with low purine content using beef broth as an example. Presented is the profile of the beef broth before (thick line) and after (thin line) enzyme treatment with (A) 4.2 U adenine deaminase (Aadap) for 20 min and (B) an enzyme mixture containing 1 U of xanthine dehydrogenase (Axorp) and 0.125 U of adenine deaminase (Aadap), guanine deaminase (Agdap) and urate oxidase (Auorp) respectively plus 3 mg ml⁻¹ NAD⁺ for 240 min. Peaks: 1 – adenine, 2 – hypoxanthine, 3 – xanthine, 4a,b – guanine, 5 – uric acid.

Table 2. Production of rolled fillet of ham with low purine content. A rolled fillet of macerated ham was incubated with the enzyme mixture consisting of adenine deaminase (Aadap), guanine deaminase (Agdap), xanthine dehydrogenase (Axorp) and urate oxidase (Auorp). The purine contents were analyzed by HPLC

		Purine amount [mg/l]
Enzyme mix [U/ml]	Incubation time[min]	Adenine	Hypoxanthine	Xanthine	Guanine	Uric acid
0	0	1.4	9.4	1.1	21.1	0
0.2	0	0.3	6.6	3.5	17.5	0
0.2	120	0	0	0.3	0	0
0.2	240	0	0	0	0	0