Team:ASIJ Tokyo/Description
Project Description
Our Incentive and Focus
Project Inspiration
In recent years, diabetes has become a matter of global concern, affecting all communities. Type II diabetes (diabetes mellitus) is a chronic condition that hinders the body’s ability to produce or properly utilize insulin, leading to high blood sugar (hyperglycemia) and associated complications. Though traditionally hailed as a ‘healthy’ country, 7.4-10.4 percent of adults in Japan are afflicted with Type II diabetes [1]. Living with diabetes is far from easy; the required involved management and control can take a sizeable mental toll. In addition to dealing with the existing stigma and the many possible health complications, (renal disease, retinopathy, neuropathy, impaired cardiovascular function etc.) diabetics also have to navigate the extensive dietary limitations imposed by their condition. Consuming foods with high glycemic indexes leads to rapid increases in blood sugar levels post-consumption and subsequent glycemic variability, exacerbating the disease and increasing the risk of complications. Glycemic variability has been found to be strongly related to the development and long-term complications of Type II diabetics [2]. With the Japanese diet being largely centered around carbohydrate-rich foods such as rice and noodles, this problem is especially relevant in Japan. The inspiration behind our project comes from our desire to minimize the dietary restrictions of diabetics. Sharing meals with friends and family is an innate part of the social fabric, and in our home country of Japan, rice and noodles are featured in nearly every meal. Although moderation is key, we hoped to find a way that diabetics could consume these foods while mitigating the negative glycemic effect they have.
Project Description
We found that one type of wheat albumin called 0.19 α-amylase inhibitor (0.19 α-AI) inhibits the function of α-amylase, minimizing blood sugar spikes by preventing the breakdown of starch into glucose [3]. We introduced various modifications to the 0.19 α-AI in an effort to increase its bonding efficiency and lifespan prior to degradation. Working in yeast, we created numerous constructs that would produce the modified 0.19 α-AI. Our final goal is to produce a food supplement with the modified 0.19 α-AI produced by yeast. Yeast is a fermenting agent in many traditional Japanese foods, including miso, koji, and sake. Our initial prototype would be focused on fermenting yeast to make miso, which is often consumed with rice. This food supplement can be consumed by diabetics and non-diabetics as a part of a healthy lifestyle and glycemic variability management regimen. We emphasize that as such a complicated affliction, extensive awareness and educational measures are paramount; the human practices portion of our project addresses this. Our end goal is to contribute to making the lives of diabetics easier, healthier, and more enjoyable.
Scroll down for more specific research and goal of our project.
Research on 0.19 α-amylase inhibitor (0.19 α-AI)
In the evolutionary process, plants have developed enzyme inhibitors against insect pests. Insects have gut digestive alpha-amylases and proteinases in order to digest the plant starch and proteins found in the plant tissue they eat. As a response defense mechanism to these insects, plants have evolved a certain degree of resistance through the production of defense compounds such as enzyme inhibitor albumin. 0.19 α-AI impedes digestion by inhibiting the activity of insect gut digestive alpha-amylases [1]. It can, therefore, be predicted that Human α-amylase would also react in this manner with its enzyme inhibitor, 0.19 α-AI. Therefore, inhibiting human salivary α-amylase activity could potentially reduce postprandial blood glucose elevation and contribute to the prevention and management of type II diabetes mellitus.
Currently, six types of albumins from kernels of hexaploid wheat, designated 0.19, 0.28, 0.32, 0.35, 0.39, and 0.48, have been found to inhibit α-amylases in human saliva, chick pancreas, yellow mealworm, Aspergillus oryzae, and Bacillus subtilis. While all albumins were shown to be strong inhibitors of yellow mealworm α-amylase, only the 0.19 albumin effectively inhibited α-amylases in human saliva, in addition to α-amylases from the yellow mealworm [2].
A homodimer with a molecular weight of 26,600 amu, 0.19 albumin is comprised of two identical 13.3-kDa subunits, composed of 124 amino acid residues associated by non-covalent interactions [3] (Figure 1). When highly purified, 0.19 albumin from Triticum aestivum (common wheat) functions as an α-amylase enzyme inhibitor. The purified 0.19 albumin acts to inhibit α-amylase in the saliva and pancreas, temporarily decreasing the α-amylase activity in the digestive tract, and slowing the absorption of starch to suppress rapid elevations of glucose levels in the blood [4].
Figure 1
Moreover, 0.19 albumin could potentially be integrated into functional foods. It has been shown to maintain stability under limited heat treatment, exhibiting 98.2% of its maximum activity for 120 minutes under 100˚C; it is far more heat-resistant than other proteins that typically denature at human body temperature [5]. Furthermore, 0.19 α-AI is water-soluble, odorless, colorless, and have already been approved for use in blood-glucose-level-suppression in Food for Special Health Uses, making it an optimal subject for a food supplement [6].
However, one limitation of 0.19 α-AI is its binding to IgE, which may cause an allergic response. Ingestion of this protein, or any food supplement derived from it, by patients allergic to wheat, may potentially result in anaphylaxis [7]. If 0.19 α-AI is utilized in a food supplement to lower blood glucose levels, potential dangers to a certain group of patients and consumer health must be carefully considered and evaluated.
Our Focus
For our project, we focused on a gap in research with 0.19 α-AI, which is the loss of inhibitory activity in the stomach. Despite its ability to suppress α-amylase, the enzyme-inhibitor complex is susceptible to protease break down once it reaches the stomach. The graph of change in blood glucose over time of Type 2 Diabetes who administered 0.19 α-AI postprandially showed a gradual increase in blood glucose for non-placebo group after (Figure 2). This indicates that enzyme-inhibitor complex is broken down in the stomach by other digestive enzymes, and the starch can bind to the uninhibited α-amylase again. Since 0.19 α-AI only delays the absorption of carbohydrates, not reduce the amount of absorption, maintaining the inhibited state becomes the key to achieving our objective of reducing blood glucose [8]. Therefore, we decided to modify the 0.19 α-AI, so that it will have a stronger binding to the α-amylase, so that it can withstand some protein cleaving by proteases.
Figure 2
