Example scientific paperHere is a "stripped down" example of a scientific paper describing the subcellular localisation of an enzyme. It gives you an idea of how to describe your methods and how to present your results. You do not need to regurgitate all the methods in a long winded way, but rather in the concise way shown below. Don't just copy this example! It is to help you with your report, with the layout and the presentation of data and the "style" of writing. This example does not include specific enzyme activity and individual recoveries in the table of results which you SHOULD include (see the instructions on writing your report in the handbook and Moodle). Your discussion section should include your conclusions as to the location of ADH in yeast. Your results may not be what you "expect". You must present your results anyway and attempt to interpret them in a scientific way. Do not be tempted to simply dismiss results as "wrong" just because they are different to the results of others. Of course you may have made mistakes, amd mixed up samples, carried out the wrong dilutions etc. This may be the explanation for "wrong" results. But unless you are convinced you have made errors of this kind you must treat your results as "correct" and provide an appropriate interpretation of them. 

Please note: I have only included RSA in this "dummy", you must report specific enzyme activity, RSA and total recovery of enzyme activity in your report (for ADH and marker enzymes) and also total protein in each fraction and total recovery of protein.

Good luck!

The Intracellular Location of a Ca2++ - stimulated Phospholipase A1 in Human BrainDr. A. Littleshot. J. Pedestrian Biochemistry 1 1-2 (1921)

SummaryHuman brain contains a phospholipase A1 which hydrolyzes phosphatidylethanolamine with a pH optimum of 9.5. The enzyme is stimulated by CaCl2and inhibited by sodium taurocholate and Triton X-100. The subcellular distribution of the enzyme is similar to that of lactate dehydrogenase indicating the location of the phospholipase in the soluble cytoplasm (cytosol) following homogenisation.

IntroductionBlah, blah, blah. A paragraph or two describing briefly the activity and function of phospholipases and finishing with:"This communication reports the presence of a phospholiase A1 enzyme activity in human brain and that the enzyme activity is located in the soluble fraction following tissue homogenisation."

MethodsHomogenisation and fractionationHuman cerebral cortex (100-150g wet weight) was homogenised in 4 volumes of 0.32M sucrose, pH 7.5, at 4oC, with 10 strokes in a Potter homogeniser. After removing an aliquot of homogenate for analysis the remainder was centrifuged at 1,000g for 10 minutes to yield a crude nuclear (P1) pellet. The post-nuclear supernatant was centrifuged at 15,000g for 30 minutes to yield pellet P2 and a supernatant which was centrifuged at 100,000g for 60 minutes to yield a pellet (P3) and a supernatant (S). The P2 pellet was further fractionated on a sucrose density step-gradient as described by Gray and Whittaker [3]. Pellets were resuspended to 10ml in 0.32M sucrose and all fractions were stored at -20oC until used.

Determination of enzyme activitiesLactate dehydrogenase (L-lactate:NAD oxdoreductase EC 1.1.1.27) was determined as described by Johnson [1]. Samples of homogenate (5-50µg of protein) and fractions were incubated at 37oC in a volume of 1ml containing 100mM phosphate pH 7.5, 10mM pyruvate and 0.3mM NADH. After 15 minutes the absorbance of the reaction mixture was measured at 340nm. The rate of formation of

NADH was calculated using the molar extinction coefficient of NADH at 340nm (6.2. 103) after correcting for the absorbance due to the reaction mixture excluding pyruvate.

NADPH-cytochrome c reductase (EC 1.6.2.4) was determined by the method of Sottocasa [2]. The optical density at 550nm of of a 3ml mixture containing 1mM NADPH, 0.5mM cytochrome c, 3mM KCN (gulp!) and 100mM sodium phosphate, pH 7.5 was incubated at 37oC was measured with a recording spectrophotometer. The reaction was initiated with the addition of NADPH and activities calculated using a molar extinction coefficient of 1.9.104 for reduced cytochrome c.

Succinate dehydrogenase, beta-galactosidase and phospholipase A1 Blah, blah, blah. 

ResultsThe relative specific activities of phospholipase A1 in the tissue fractions correlated (correlation coefficient = 0.98) with those of lactate dehydrogenase, and not with any other marker enzyme (Table 1).

Table 1 Phospholipase A1 activity in subcellular fractions of rat brain cerebral cortex.

Fraction Protein recovered (%)

Phospholipase A1 RSA

Lactate dehydrogenase RSA

Succinate dehydrogenase RSA

Homogenate - 1.00 1.00 1.00

P1 28.7 0.37 0.36 0.93

P2A 3.1 0.00 0.04 0.00

P2B 9.5 0.00 0.42 0.00

P2C 10.4 0.01 0.61 3.96

P3 6.2 0.09 0.64 0.00

S 15.0 2.94 2.87 0.00

As phospholipase A1 enzyme activity is concentrated in the supernatant fraction we may conclude that phospholipase A1 in human brain is a soluble protein and is probably resident in the cytosol. The suggests that phospholipase A1 activity is located in the cytosol of human brain, or at least the soluble cytoplasm following homogenisation. 

Blah. blah.

ReferencesBlah, blah, blah.

AcknowledgementsI would like to thank my faithful technician Igor for all his help in obtaining brains and other body parts.