Methanol is an important intermediate in the utilization of natural gas for synthesizing other feedstock chemicals. Typically, chemical approaches for building C-C bonds from methanol require high temperature and pressure. Biological conversion of methanol to longer carbon chain compounds is feasible; however, the natural biological pathways for methanol utilization involve carbon dioxide loss or ATP expenditure. Here we demonstrated a biocatalytic pathway, termed the methanol condensation cycle (MCC), by combining the nonoxidative glycolysis with the ribulose monophosphate pathway to convert methanol to higher-chain alcohols or other acetyl-CoA derivatives using enzymatic reactions in a carbonconserved and ATP-independent system. We investigated the robustness of MCC and identified operational regions. We confirmed that the pathway forms a catalytic cycle through 13 C-carbon labeling. With a cell-free system, we demonstrated the conversion of methanol to ethanol or n-butanol. The high carbon efficiency and low operating temperature are attractive for transforming natural gas-derived methanol to longer-chain liquid fuels and other chemical derivatives.ethanol is industrially produced from synthetic gas-derived olefins and alkanes (1-7). These reactions typically involve high temperatures and pressures that require large capital investment (8, 9). The condensation of methanol to higher-chain alcohols such as ethanol or n-butanol is thermodynamically favorable (ΔG°′ = −68 and −182 kJ/mol, respectively), but the direct condensation of methanol to higher-chain alcohols has been quite challenging. Using the Guerbet reaction, methanol can upgrade short alcohols (such as n-propanol) to longer alcohols; however, methanol cannot self-couple (10). Metal acetylides can convert methanol to isobutanol, although this process was demonstrated to be noncatalytic (11).Nature has evolved several distinct ways to assimilate methanol to form metabolites necessary for growth. In principle, metabolites resulting from these methylotrophic pathways can be used to form higher-chain alcohols, although inherent pathway limitations prevent complete carbon conservation (Fig. S1). In the ribulose monophosphate pathway (RuMP), three formaldehydes condense to pyruvate, which is decarboxylated to form acetyl-CoA and CO 2 , reducing the carbon efficiency to 67%. The serine pathway requires an external supply of ATP to drive otherwise unfavorable reactions. Similarly, oxidation of methanol to CO 2 followed by CO 2 fixation using the Calvin-Benson-Bassham (CBB) cycle also requires additional ATP. To generate the required ATP input, extra carbon must be spent to drive oxidative phosphorylation. To our knowledge, natural methylotrophs are not capable of using the reductive acetyl-CoA pathway, which can produce acetyl-CoA without carbon loss or ATP requirement through carbon reassimilation after complete oxidation of methanol. This route is extremely oxygen sensitive and difficult to engineer due to the complex cofactors involved, and achieving carbo...

Stability in a metabolic system may not be obtained if incorrect amounts of enzymes are used. Without stability, some metabolites may accumulate or deplete leading to the irreversible loss of the desired operating point. Even if initial enzyme amounts achieve a stable steady state, changes in enzyme amount due to stochastic variations or environmental changes may move the system to the unstable region and lose the steady-state or quasi-steady-state flux. This situation is distinct from the phenomenon characterized by typical sensitivity analysis, which focuses on the smooth change before loss of stability. Here we show that metabolic networks differ significantly in their intrinsic ability to attain stability due to the network structure and kinetic forms, and that after achieving stability, some enzymes are prone to cause instability upon changes in enzyme amounts. We use Ensemble Modelling for Robustness Analysis (EMRA) to analyze stability in four cell-free enzymatic systems when enzyme amounts are changed. Loss of stability in continuous systems can lead to lower production even when the system is tested experimentally in batch experiments. The predictions of instability by EMRA are supported by the lower productivity in batch experimental tests. The EMRA method incorporates properties of network structure, including stoichiometry and kinetic form, but does not require specific parameter values of the enzymes.

Purpose Health care research increasingly relies on assessment of data extracted from electronic medical records (EMRs). Clinical trial adverse event (AE) logs and patient-reported outcomes (PROs) are sources of data often available in the context of specific research projects. The aim of this study was to evaluate the extent of data concordance from these sources. Patients and Methods Patients enrolled in clinical trials or receiving standard treatment for lung cancer (n = 62) completed validated questionnaires on physical and psychological symptoms at up to three assessment points. Temporally matched documentation was extracted from EMR notes and, for clinical trial participants (n = 41), AE logs. Evaluated data included symptom assessment, vital signs, medication logs, and laboratory values. Agreement (positive, negative) and Cohen’s κ coefficients were calculated to assess concordance of symptoms among sources, with PROs considered the gold standard. Results Patient-reported weight loss correlated significantly with clinical measurements (t = 2.90; P = .02), and average number of PROs correlated negatively with albumin concentration, supporting PROs as the gold standard. Comparisons of PROs versus EMR yielded poor concordance across 11 physical symptoms, anxiety, and depressive symptoms (all κ < 0.40). Providers under-reported the presence of each symptom in the EMR compared with PROs. AE logs showed similarly poor concordance with PROs (all κ < 0.40, except shortness of breath). Negative agreement among sources was higher than positive agreement for all symptoms except pain. Conclusion There was poor concordance between EMR notes and AE logs with PROs. Findings suggest that EMR notes and AE logs may not be reliable sources for capturing physical and psychological symptoms experienced by patients with lung cancer, supporting use of PRO assessments in oncology practices.

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