Catalases are well studied enzymes that play critical roles in protecting cells against the toxic effects of hydrogen peroxide. The ubiquity of the enzyme and the availability of substrates made heme catalases the focus of many biochemical and molecular biology studies over 100 years. In human, this has been implicated in various physiological and pathological conditions. Advancement in proteomics revealed many of novel and previously unknown features of this mysterious enzyme, but some functional aspects are yet to be explained. Along with discussion on future research area, this mini-review compile the information available on the structure, function and mechanism of action of human catalase.

Increased serum malondialdehyde in oral cancer and oral precancer would serve as a valuable marker for both preventive and clinical intervention, and may deserve further investigation for the early diagnosis, treatment, and prognosis.

Objective: Interaction between reactive oxygen species (ROS) and reactive nitrogen species (RNS) is a crucial determinant in the etiology of oral squamous cell carcinoma (OSCC), and antioxidants protect against cellular and molecular damage caused by these. This study aims to evaluate ROS and RNS, together with the total antioxidant capacity (TAC), in serum and tissues of OSCC patients. Method: Total nitric oxide (TNO), malondialdehyde (MDA), and TAC were evaluated using a UV visible spectrophotometer in the serum of 30 controls, 30 precancer and 30 OSCC patients and in tissues of 10 controls and 30 OSCC patients. Results: MDA and TNO were significantly elevated with concomitant depletion of TAC in serum and tissues of OSCC patients when compared to controls. A significant positive correlation (p = 0.01), at different levels between TNO and MDA in OSCC patients, was found, which increased with the grade of OSCC. Conclusion: An increase in the levels of TNO, NO-mediated lipid peroxidation, resulting in an increase in MDA levels, the positive TNO-MDA correlation with a deranged antioxidant defense system as demonstrated by significantly low levels of TAC; when all these facts are taken together, we can conjecture that oxidative DNA damage, a vital phenomenon for carcinogenesis, occurs due to the interplay of ROS, RNS and TAC.

A rapid and inexpensive plasma glucose estimation by two-point kinetic method based on glucose oxidase and peroxidase enzymes has been developed. It takes only 1½ minutes of time and validity of the method has been discussed.

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