Page 140 - Malaysian Journal of Health Promotion, Vol 4 (Supplementary 1) 2022

Malaysian Journal of Health Promotion, Vol 4 (Supplementary 1) 2022
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14 MOH-AMM Scientific Meeting 2022 in conjunction with 23 NIH Scientific Conference Abstract Book
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1 Inborn Errors of Metabolism & Genetics Unit, Nutrition, Metabolism & Cardiovascular Research Centre,
Institute for Medical Research, National Institutes of Health, Ministry of Health
2 Faculty of Science and Marine Environment, Universiti Malaysia Terengganu

INTRODUCTION: Arylsulphatase A (ARSA) is a lysosomal enzyme and its deficiency is
responsible for metachromatic leukodystrophy. Currently, many marketed medications
function by inhibiting enzymes that mediate disease characteristics. These chemicals are
frequently competitive, reversible inhibitors of substrate binding. Complete understanding of
enzyme biochemistry and action is essential. Thus, this study aimed to assess the implication
of glucose against ARSA activity.
METHODS: Six independent plasma samples spiked with glucose in several concentrations
were plated and incubated (37°C, 1 hour) with 1:1 ratio of sample and p-nitrocatechol
sulphate. The reaction was terminated with 0.2 M sodium hydroxide and ρ-nitrocatechol
produced were measured using spectrophotometer (515nm). Results were determined as
amount of p-nitrocatechol in nmol per ml per hour (nmol/ml/hour). Descriptive analysis was
performed using IBM SPSS version 22. Kruskal-Wallis test was performed to compare
differences between group while Mann-Whitney test was performed to compare for two
groups.
RESULTS: ARSA activity in control group was observed as non-parametric. Median were
160.29 nmol/ml/hr with min and max value of 141.82 and 216.91 nmol/ml/hr, respectively.
ARSA activity was found significantly reduced in plasma spiked with glucose compared to
baseline plasma (p=0.004) at the level of 1.1 mM. Percentages of ARSA inhibition in the
glucose concentration of 1.1 mM, 2.2 mM, 3.3 mM, 4.4 mM, 5.6 mM and 8.3 mM were 72%,
68%, 58%, 47%, 40% and 22%, respectively.
DISCUSSION/CONCLUSION: The outcomes support the possibility of glucose to act as an
inhibitor affecting ARSA activity. This finding, however, has to be investigated further by
performing kinetic study of ARSA with glucose.

ID 184 POSSIBLE INTERFERENCE OF LACTOSE IN ARYLSULPHATASE A ASSAY

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Nur Jannaim Muhamad , Affandi Omar , Salina Abdul Rahman , Fatimah Diana Amin Nordin , Balqis Kamarudin ,
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Fatin Nurin Najma Latif , Julaina Abdul Jalil 1
1 Inborn Errors of Metabolism & Genetic Unit, Nutrition, Metabolism & Cardiovascular Research Centre (NMCRC),
Institute for Medical Research, National Institutes of Health, Shah Alam, Selangor, Malaysia
2 Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Kuala Terengganu, Terengganu,
Malaysia

INTRODUCTION: Metachromatic leukodystrophy (MLD) demonstrates deficiency in
Arylsulphatase A (ARSA) enzyme. An investigation into possible interference in ARSA assay
with lactose was carried out. A rapid instrumental colorimetric assay for ARSA using p-
nitrocatechol sulphate (pNCS) as substrate, was used to investigate activity of this enzyme
towards lactose in plasma from suspected patients with metachromatic leukodystrophy.
METHOD: Different concentrations of lactose were spiked into six independent plasma
samples. ARSA activities in spiked plasma samples were determined by measuring the
amount of p-nitrocatechol (pNC) liberated from pNCS. The amount of pNC liberated was
determined with spectrophotometer by measuring the absorbance at 515 nm. Kruskal-Wallis
test was performed to compare any difference between group while Mann-Whitney test was
performed to compare for two groups.

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