The Effect of a Peptide Substrate Containing an Unnatural Branched Amino Acid on Chymotrypsin Activity

7-Amino-4-methylcoumarin (AMC) is a low molecular weight fluorescent probe that can be attached to a peptide to enable the detection of specific proteases, such as chymotrypsin, expressed in certain diseases. Because this detection depends on the specificity of the protease toward the peptidyl AMC, the development of specific substrates is required. To investigate the specificity of chymotrypsin, peptidyl AMC compounds incorporating four different amino acid residues were prepared by liquid-phase synthesis. Two unnatural amino acids, 2-amino-4-ethylhexanoic acid (AEH) and cyclohexylalanine (Cha), were used to investigate the substrate specificity as these amino acids have structures different from natural amino acids. AEH was synthesized using diethyl acetamidemalonate as a starting material. The substrate containing Cha had high hydrophobicity and showed a high reaction velocity with chymotrypsin. Although the AEH substrate with a branched side chain had high hydrophobicity, it showed a low reaction velocity. The substrate containing the aromatic amino acid phenylalanine was less hydrophobic than the Cha and AEH substrates, but chymotrypsin showed the highest specificity for this compound. These results demonstrated that the substrate specificity of chymotrypsin is not only affected by the hydrophobicity and aromaticity, but also by the structural expanse of amino acid residues in the substrate.

Performance Comparison of Fe2+ Activated Persulfate and Electro-Persulfate Process in Acid Blue 25 Removal from Aqueous Solution Operating: Conditions and Reaction Velocity

The purpose of this study was to compare the performance of Fe2+ activated persulfate and electro-persulfate process in Acid Blue 25 removal from aqueous solution. For this reason, the effects of different parameters including pH, dye, sodium persulfate and ferrous sulfate concentrations were investigated. The removal efficiency of 92% at the time of 60 min was obtained at pH= 3, dye concentration= 50 mg/L, sodium persulfate concentration= 500 mg/L and Fe (II) sulfate concentration= 100 mg/L for Fe2+ activated persulfate system and the removal efficiency of 95% at pH= 5, dye concentration = 200 mg/L, sodium persulfate concentration = 500 mg/L and ferrous sulfate concentration = 100 mg/L for electro-persulfate system by means of graphite materials as the neutral electrodes. COD removal efficiency in Fe2+ activated persulfate and electro-persulfate in the mentioned conditions were 90% and 89% in 180 minutes, respectively. Moreover, the result of process kinetics showed that using electrochemical process improved the reaction velocity from 0.0016 to 0.0487 mg/L/min. The comparison between these two-process showed that using electrochemical process improved dye removal efficiency by 4 times.

Enzymatic Synthesis of Glucose Monodecanoate in a Hydrophobic Deep Eutectic Solvent

Environmentally friendly and biodegradable reaction media are an important part of a sustainable glycolipid production in the transition to green chemistry. Deep eutectic solvents (DESs) are an ecofriendly alternative to organic solvents. So far, only hydrophilic DESs were considered for enzymatic glycolipid synthesis. In this study, a hydrophobic DES consisting of (-)-menthol and decanoic acid is presented for the first time as an alternative to hydrophilic DES. The yields in the newly introduced hydrophobic DES are significantly higher than in hydrophilic DESs. Different reaction parameters were investigated to optimize the synthesis further. Twenty milligrams per milliliter iCalB and 0.5 M glucose resulted in the highest initial reaction velocity for the esterification reaction, while the highest initial reaction velocity was achieved with 1.5 M glucose in the transesterification reaction. The enzyme was proven to be reusable for at least five cycles without significant loss of activity.

On the Velocity of Enzymatic Reactions in Michaelis–Menten-Like Schemes (Ensemble and Single-Molecule Versions)

In searching non-standard ways of conformational regulation, various Michaelis–Menten-like schemes attract relentless attention, resulting in sometimes too sophisticated considerations. With the example of monomeric enzymes possessing an only binding site, we define the minimal schemes capable of bearing peculiar regulatory properties like “cooperativity” or substrate inhibition. The simplest ways of calculating the enzymatic reaction velocity are exemplified, either in the ensemble or single-molecule case.

An approach to better estimation of the intial velocity of enzyme reactions

A new algorithm for computation of initial velocity of enzyme reaction at the time zero is proposed. This algorithm makes it possible to reduce systematic error of measurements to the minimum, to estimate reaction velocity in testing samples regardless of the enzyme activity levels and to minimize assay time. The study is illustrated by an example of salivary alpha-amylase and standard reagent kit. The algorithm should not be applied if conjugated enzyme systems are used because there is a long initial lag-phase in the kinetic curve.

Penggunaan Media iMindMap7 pada Model Pembelajaran Kooperatif tipe STAD (Studi tentang Hasil Belajar Siswa Kelas XI-IPA 1 MAN 2 Model Makassar pada Materi Pokok Laju Reaksi)

ABSTRAK Penelitian ini adalah penelitian pra-eksperimen dengan tujuan untuk mengetahui hasil belajar siswa kelas XI IPA 1 di MAN 2 Model Makassar yang dibelajarkan melalui penggunaan media iMindMap pada model pembelajaran koopertaif tipe STAD. Variabel bebas dalam penelitian ini adalah media iMindMap pada model pembelajaran kooperatif tipe STAD sedangkan variabel terikatnya adalah hasil belajar dengan aktivitas siswa pada materi pokok laju reaksi. Subjek penelitan adalah kelas IX IPA 1 yang berjumlah 30 siswa. Desain Penelitian yang digunakan adalah One Group Pretest-Posttest Design. Pengambilan data hasil penelitian dilakukan dengan lembar observasi dan pemberian Tes Hasil Belajar (THB) sebanyak 20 nomor yang telah divalidasi. Data yang diperoleh dianalisis dengan menggunakan analisis deskriptif dan N-gain. Hasil analisis deskriptif menunjukkan skor rata-rata hasil belajar siswa sebelum dibelajarkan dengan menggunakan media pembelajaran iMindMap pada model pembelajaran kooperatif tipe STAD adalah 35,66 dengan standar deviasi sebesar 8,78 dan setelah dibelajarkan dengan menggunakan media pembelajaran iMindMap pada model pembelajaran kooperatif tipe STAD adalah 78,33 dengan standar deviasi 8,23. Berdasarkan hasil analisis N-Gain diperoleh peningkatan gain sebesar 35%. Hal ini dapat disimpulkan bahwa aktivitas dan hasil belajar setelah dibelajarkan dengan menggunakan media iMindMap pada model pembelajaran kooperatif tipe STAD kelas XI IPA 1 MAN 2 Model Makassar mengalami peningkatan.Kata Kunci: iMindMap, STAD, hasil belajar, aktivitas ABSTRACTThis study is a pre-experimental research that aims to determine learning outcomes of XI Exact 1 Students in MAN 2 Model Makassar that has been studied among used iMindMap media in Cooperative Learning Model type STAD. The iMindMap media in Cooperative Learning Model type STAD as independent variables and the study result with the activity of the students on reaction velocity as a dependent variabel. The subject in this research is all students of XI Exact 1 Class MAN 2 Model Makassar that consist of 30 students. One Group Pretest-Posttest Design is a design that used in this research. The data was collected by observation sheet and by giving 20 validated tems of study result test. The data was analyzed by descriptive analysis and N-gain. The result of descriptive analysis show the mean score of study result before studied with use iMindMap Media in Cooperative Learning Model type STAD is 35,66 with deviation standar 8,78 and has been studied with use iMindMap Media in Cooperative Learning Model type STAD is 78,33 with deviation standar 8,23. Base on N-Gain analysis show the gain is 35%. It is means that the used of iMindMap Media in Cooperative Learning Model Type STAD XI Exact 1 Class MAN 2 Model Makassar increased.Keywords : iMindMap, STAD, study result, activity