![]() The calculator below may also be used in these other instances where the units of activity are used in a similar manner to that described above for enzymes. The shorter lifetimes of Tr* and R* in cones seem to explain the remaining difference in the effectiveness of PDE activation between rods and cones.It is also important to note that other units of activity exist for various biologically active molecules, and each is defined in a unique way according to a standard established by experts in the field. The effect of Tr* inactivation was larger in cones, probably because the lifetime of Tr* is shorter in cones than in rods. This is probably because inactivation of Tr* shortened its lifetime, thereby reducing the number of activated PDE molecules. In a comparison of PDE activation in the presence (with GTP) and absence (with GTPγS) of Tr* inactivation, PDE activation required more light (and was therefore less effective) when Tr* was inactivated in both rod and cone membranes. Next, we examined the contribution of R* and Tr* lifetimes. By activating PDE with known concentrations of the active (guanosine 5′-Ο-(γ-thio)triphosphate (GTPγS)-bound) form of Tr*, we found that Tr* activated PDE at a similar efficiency in rods and cones. ![]() First, we examined the efficiency of activation of PDE by activated Tr (Tr*). In this study, we tried to explain the remaining difference. The lower effectiveness of PDE activation in carp cones is due partly to the fact that the activation rate of transducin (Tr) by light-activated visual pigment (R*) is 5-fold lower in carp cones than in rods. We showed previously in carp that more light (>100-fold) is required in cones than in rods to activate 50% of cGMP phosphodiesterase (PDE). Optimized medium by OFAT and RSM enhanced enzyme production by 7.5-folds confirming the need to optimize the production parameters to achieve maximum yield.Ĭones are less light-sensitive than rods. The model showed higher amylase activity of 3.6 and 7.5-fold as compared to the basal and the initial media, respectively. The model validation was clear up on comparing the statistical predicted yield (140.14 U/ml) with the actual experimental yield (145.4 U/ml) of α-amylase which was closely related. Whereas MnCl 2♴H 2O, soluble starch and culture pH showed negative effect on α-amylase production. Among thirteen independent variables tested in PB design, beef extract, MgSO 4♷H 2O, K 2HPO 4 and incubation time were the most significant on α-amylase production and showed positive effect. The most significant factors were identified and its values were optimized using Plackett-Burman (PB) and Central Composite (CC) design, respectively. The result obtained from OFAT showed 72.4U/ml of amylase activity which was 1.8- fold higher as compared to unoptimized conditions (40.3 U/ml). ![]() α-Amylase production parameters were optimized using one-factor-at-a-time (OFAT) and Response Surface methodology (RSM). This sequence was deposited to the GenBank under accession number, B. The most potent isolate MK1 was identified (morphologically and biochemically) and confirmed by 16S rRNA gene sequence method. Screening was done by iodine test, based on the clear zone around the sample in starch agar plates. In the present study, α-amylase producers were isolated from farm soil in Egypt (Sadat City). Α-amylase is a starch hydrolyzing enzyme which has many industrial applications. The results also indicate that at least 72% of the normal urinary α-amylase found in the water-load test is of pancreatic origin. This simple test, which can be made without a specialized gastroenterology department, could serve as a valuable aid in the laboratory diagnosis of pancreatic insufficiency. By contrast, the values for the urinary excretion of α-amylase showed little overlap of the results of the two series of subjects (only one value in the pathological series was above the suggested normal lower limit). Amylase clearance was significantly decreased in the pathological series, but the total overlap of the results precludes the use of serum α-amylase measurements as a diagnostic aid in pancreatic insufficiency. Both the mean serum α-amylase values and the urinary excretion of α-amylase during 2 h after intake of 500 ml of water were low in the pathological series and differed highly significantly from the values of the control groups. ![]() The α-amylase was measured with a new, accurate and sensitive chromogenic method (Phadebas Amylase Test, Pharmacia, Sweden). A group of 23 patients with suspected pancreatic insufficiency having a maximal bicarbonate concentration of less than 70 mmole/1 in the duodenal aspirate after secretin stimulation was compared with normal subjects with regard to serum α-amylase values and urinary α-amylase excretion.
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