Lowry assay

Protein quantitation is often necessary before processing protein samples for isolation, separation and analysis by chromatographic, electrophoretic and immunochemical techniques. Depending on the accuracy required and the amount and purity of the protein available, different methods are appropriate for determining protein concentration. One of the methods to determine protein concentration by using Lowry protein assay.The Lowry protein assay is named after Oliver H. Lowry, who developed and introduced it (Lowry, et al., 1951). It offered a significant improvement over previous protein assays and his paper became one of the most cited references in life science literature for many years. The Modified Lowry Protein Assay uses a stable reagent that replaces two unstable reagents described by Lowry. Protein assay methods provide greater speed and convenience, the Lowry method remains a popular, accurate and useful option for many applications

For the solutions of gelatin, as my reference graph above, we should get a linear graph, but in our findings as mentioned above, we didn’t get a linear graph. This will contribute to the presence of bubbles in the solution of gelatin in cuvette. Besides, the Lowry total protein assay has withstood the test of time, there are several features of the assay that have to be kept in mind. Because these methods rely on the presence of readily oxidizable amino acids such as tyrosine, cysteine, and tryptophan there is a variation in response from proteins with differing amino acid content. Therefore it is advisable that the protein used for generating the standard curve be consistent from experiment to experiment. Likewise, an overabundance of the amino acids in relation to the assay reagents, as would occur with high protein level, will result in a loss of linearity of the assay. In extreme cases this will lead to a precipitation of the chromogens and loss of color prematurely. Likewise, the assay color is only stable for approximately one hour, after which a similar phenomenon occurs in samples with normal concentrations. For our conclusion, the concentration of gelatin contribute with absorbance of light at spectrophotometer. Higher the concentration of gelatin will give higher absorbance of light recorded at spectrophotometer.

Egg selection can be difficult considering the wide array of options available. Should you choose Grade A or Grade AA? Jumbo or Large?

Egg size and quality don't necessarily have a lot to do with the state of the planet, but they do have a lot to do with your individual nutrition - and your health can certainly be green in it's own right! Whether you have or haven't made the switch to organic foods, it's important to make your diet as healthy as you think it is.

When it comes to eggs, the most basic choice you have involves size and quality. Even though they are listed side by side on the carton, egg size and egg quality are not related. Read on to find out how to select your eggs by size and grade, and how such seemingly small decisions can affect your personal health.

The protein contained in the eggs also can be determined by using the protein assay method such as the Lowry method. Egg protein is very rich in quality and it is due to this fact that manufacturers of protein powders often base their products on egg protein. Egg protein contains all the essential amino acids that the human body requires. From our experiment, as mentioned in above, the duck egg contains highest protein than other sample of eggs. Among the sample of egg A, B and C, the concentration of protein of sample egg B (1.439mg/L) contain more protein than sample of egg A (1.134mg/L) and C (1.033mg/L). The sample of egg B has higher absorbance of light (nm) than grade egg A and C. Higher absorbance of light (nm) show higher concentration of protein (mg/L). So, sample of egg B contain higher protein than egg A and C. As we know that, size egg A is bigger than egg B and egg C. From the findings show us that size of egg did not give the effect of protein contain in egg. The egg A is bigger than the others but the contain of protein in that egg is not high as it size.

When we compare the concentration of protein between sample x and sample B, the concentration of protein in sample B (1.439 mg/L) is higher than the concentration of protein in sample x (1.327 mg/L). However, when we compare it with sample A (1.134mg/L) and sample C (1.033mg/L) with sample x (1.327mg/L), the concentration of protein in sample x is higher than the concentration of protein in sample A and C.

Here, I would like to share you some information about egg selection by quality.

Chef or not, you may be surprised how egg grade can effect a dish's final outcome. Grades range from AA to C, though Grade C eggs are not available for consumer purchase.

Quality standards are as follows:

• Grade AA: Eggs of the highest quality have shells that are clean, unbroken and are shaped like a typical egg. The egg white is clear, firm, and springy, while the egg yolk is well-centered, free from defects and has a slightly defined outline.

Grade AA eggs are ideal for any use, but are particularly desirable for frying, poaching, and hard boiling.

• Grade A: Grade A eggs have shells that are very similar to higher graded eggs - they will be clean, unbroken and normally-shaped. The egg white will be clear and reasonably firm, though it won't stand as high as Grade AA egg whites. The yolk will be fairly well centered, free from defects, and it will have a fairly well-defined outline.

Grade A eggs are well suited for frying, poaching, and hard boiling, though they can be used for any purpose.

• Grade B: These lower grade eggs may have a shell that is clean or slightly stained. The shell will be unbroken, but may be weak or abnormally shaped. The egg white will be clear, though not springy, and the yolk may be slightly off center, enlarged and have minor (not serious) defects.

Grade B eggs are relatively flat when cracked compared to Grade AA and Grade A eggs. For this reason, Grade B eggs are best suited for scrambling, baking, or use as ingredients.

• Grade C: Grade C eggs will have clean to moderately stained shells. Shells will be unbroken, but may be abnormally shaped. The egg white will be flat and watery, and small blood clots or spots may be present. The yolk may be off center, enlarged and flattened and may show serious defects. The yolk outline will be plainly visible.

Grade C eggs are not sold directly to consumers.

Contrary to popular belief, egg 'grade' or 'quality' has nothing to do with nutritional value. Instead, the grade an egg receives has to do with the egg's shell quality and how the egg stands once it's cracked - two things that have more to do with food preparation than they have to do with food safety.

As a conclusion, from this experiment show us that the grade of eggs will not give best concentration of protein in it. Although grade eggs B is smaller than grade eggs A, it will give you more benefit to your health than grade eggs A. So, from now on, if you want to buy the eggs grade A you have to think about its protein concentration and that eggs must be more expensive than grade eggs B.