The effect of amino acid deletions and substitutions in the longest loop of GFP

Background  

The effect of single and multiple amino acid substitutions in the green fluorescent protein (GFP) from Aequorea victoria has been extensively explored, yielding several proteins of diverse spectral properties. However, the role of amino acid deletions in this protein -as with most proteins- is still unknown, due to the technical difficulties involved in generating combinatorial in-phase amino acid deletions on a target region.     

Estimation of temperature dependent parameters of a batch alcoholic fermentation process

In this work, a procedure was established to develop a mathematical model considering the effect of temperature on reaction kinetics. Experiments were performed in batch mode in temperatures from 30 to 38 degrees C. The microorganism used was Saccharomyces cerevisiae and the culture media, sugarcane molasses. The objective is to assess the difficulty in updating the kinetic parameters when there are changes in fermentation conditions. We conclude that, although the re-estimation is a time-consuming task, it is possible to accurately describe the process when there are changes in raw material composition if a re-estimation of parameters is performed.     

Hybrid neural network model of an industrial ethanol fermentation process considering the effect of temperature

In this work a procedure for the development of a robust mathematical model for an industrial alcoholic fermentation process was evaluated. The proposed model is a hybrid neural model, which combines mass and energy balance equations with functional link networks to describe the kinetics. These networks have been shown to have a good nonlinear approximation capability, although the estimation of its weights is linear. The proposed model considers the effect of temperature on the kinetics and has the neural network weights reestimated always so that a change in operational conditions occurs. This allow to follow the system behavior when changes in operating conditions occur.     

Single and double A3-coupling (aldehyde-amine-alkyne) reaction catalyzed by an air stable copper(I)-phosphole complex

An air stable copper(I)-phosphole complex, [CuCl{2,5-bis(2-thienyl)-1-phenylphosphole}₂] (1), was utilized as a catalyst in single and double A³-coupling reactions for preparing mono- and bi-propargylamines. A variety of aldehydes, amines and terminal alkynes were tested. Most of these reactions led to formation of the expected propargylamines in good yields using low amounts catalyst and obviating both the use of purified reagents as employ of a glovebox.     

Front Cover: Katritzky Salts for the Synthesis of Unnatural Amino Acids and Late-Stage Functionalization of Peptides (Eur. J. Org. Chem. 12/2023)

Peptide drug discovery often benefits from the large structural diversity permitted by unnatural amino acids (UAAs). Indeed, numerous approved peptide drugs include UAAs in their sequences. Therefore, innovative chemical approaches either to synthesize UAAs or to allow late-stage functionalization of peptides are emerging themes in peptide drug discovery. Thanks to the recent advances in deaminative strategies using alkylpyridiniums salts, often referred to as Katritzky salts, a variety of radical alkylation methods have been developed. In recent years the use of Katritzky salts have become popular in peptide chemistry due to their ease of preparation from a primary amine, which is a predominant functional group in amino acids. This review highlights the progress that has been made by using Katritzky salts in the synthesis of UAAs, late-stage peptide functionalization, and peptide macrocyclization.     

STUDIES ON THE UV PHOTODESTRUCTION OF PURINE FREE BASE IN AQUEOUS SOLUTIONS AT 77 and 298K

Abstract— The photodestruction of purine free base used as a model for the purine bases in DNA has been studied in order to better understand the effect of UV light on these molecules. Photodestruction yields have been determined in glassy aqueous solutions at 77 K and at room temperature at different pH's. The yield decreases in the order of 0.04, 0.01, 0.001 in 8 M NaOH, 8 M NaCIO₄ and 6 M H₃PO₄, respectively, while at room temperature the highest destruction yield is 0.005 for the unbuffered neutral solution. These yields have been determined by measuring the initial decrease in the purine absorption maximum as a function of irradiation time. During the illumination stable photoproducts, as well as reactive intermediates, such as trapped electrons, radical anions and cations, are formed and have been characterized from their absorption spectra. The addition of triplet quenchers and an electron scavenger resulted in a decrease in the yield, implying the participation of the purine triplet state and a radical anion in the reactions leading to the photodestruction of purine.     

Monotonic bounds in multistage mixed-integer stochastic programming

Multistage stochastic programs bring computational complexity which may increase exponentially with the size of the scenario tree in real case problems. For this reason approximation techniques which replace the problem by a simpler one and provide lower and upper bounds to the optimal value are very useful. In this paper we provide monotonic lower and upper bounds for the optimal objective value of a multistage stochastic program. These results also apply to stochastic multistage mixed integer linear programs. Chains of inequalities among the new quantities are provided in relation to the optimal objective value, the wait-and-see solution and the expected result of using the expected value solution. The computational complexity of the proposed lower and upper bounds is discussed and an algorithmic procedure to use them is provided. Numerical results on a real case transportation problem are presented.