It is time to crowd your cell culture media – Physicochemical considerations with biological consequences

Stochastic pH Oscillations in a Model of the Urea–Urease Reaction Confined to Lipid Vesicles

“…Indeed, the cytoplasm is a highly heterogeneous medium exhibiting macromolecular crowding and compartmentalization, with repercussions on the reaction kinetics. [20][21][22][23] Enzymatic activity is confined to small reaction chambers ranging from about 10 µm for lipid membrane organelles 24 down to 20 nm for bacterial microcompartments 25,26 and outer membrane vesicles. 27,28 Such small compartments can host only very limited copy numbers of molecules, necessitating the replacement of RREs by their discrete and inherently stochastic counterparts.…”

“…Furthermore, there is a growing interest in chemical oscillators for applications. − This motivates the question whether stable limit cycles persist and how they change upon downscaling from the macroscopic to, e.g., intracellular reaction volumes. Indeed, the cytoplasm is a highly heterogeneous medium exhibiting macromolecular crowding and compartmentalization, with repercussions on the reaction kinetics. − Enzymatic activity is confined to small reaction chambers ranging from about 10 μm for lipid membrane organelles down to 20 nm for bacterial microcompartments , and outer membrane vesicles. , Such small compartments can host only very limited copy numbers of molecules, necessitating the replacement of RREs by their discrete and inherently stochastic counterparts. − Intrinsic noise as a result of such molecular discreteness leads to a breakdown of the macroscopic theory of Michaelis–Menten kinetics. − For monostable reaction networks, not only the size of fluctuations , but also the mean concentrations , become volume-dependent. Furthermore, intrinsic noise may change the stability of steady states, inducing oscillations in deterministic systems without limit cycles, , or alter the characteristics of limit cycles .…”

A Beefy-R culture medium: replacing albumin with rapeseed protein isolates

“…Thus, hexane defatting was avoided in generating Beefy-R due to the potential negative environmental impacts associated with this solvent. Additionally, to compare the efficacy of RPI with other potential albumin-replacing supplements, these same short-term experiments were performed using B8 supplemented with candidates including cyclodextrins 24 , off-the-shelf plant protein hydrolysates 25 , and molecular crowding agents 26 . However, none of these supplements were able to recover the efficacy of recombinant albumin in culture (Fig.…”

Macromolecular crowding: how shape and interaction affect the structure, function, conformational dynamics and relative domain movement of a multi-domain protein

“…Size dependency was studied in detail (taking a series of PEGs and dextran) as it is believed that the excluded volume effect is the main player to control the macromolecular crowding effect. [1][2][3]6,[28][29][30][31][32][33][34][35][36][37][38][39] Nonetheless, recent experimental results stipulated that the macromolecular crowding effect is controlled by a complex interplay between entropic and enthalpic factors. 1,4,8,11,14,15,20,28,30,32,34,36 The entropic element is influenced not only by the positional restriction provided by the crowder (excluding volume) but also by the positional restriction of water, 40 the pressure exerted by the crowder on the protein surface, 36,37,39 and the entropy change of associated water due to water structure perturbation.…”