Some Key Questions

What Factors Impede Enzymatic Hydrolysis and/or Substrate Transport  

FIGURE 3 Several hypothetical scenarios which might explain resistance of organic macromolecules to extracellular enzymatic hydrolysis (a) natural substrates are not a good fit for enzyme active sites, perhaps because of biological or chemical modifications (b) specific substrates are too dilute to induce enzymes under most circumstances (c) substrates are physically protected from hydrolysis (e.g., Mayer, 1994 Keil et al., 1994). Enzymes may also be complexed, hindering their activities (Wetzel, 1993). 

Physical or chemical modification of a substrate may additionally selectively affect transformation or uptake Keil and Kirchman (1992) compared the degradation of Rubisco uniformly labeled with 3H amino acids produced via in vitro translation to Rubisco that was reductively methylated with 3H-methane. Although both Rubisco preparations were hydrolyzed to lower molecular weights at approximately the same rate, little of the methylated protein was assimilated or respired. The presence of one substrate may also inhibit uptake of another, as has been demonstrated for anaerobic rumen bacteria. Transport and metabolism of the monosaccharides xylose and arabinose were strongly reduced in Ruminococcus albus in the presence of cellobiose (a disaccharide of glucose), likely because of repression of pentose utilization in the presence of the disaccharide. Glucose, in contrast, competitively inhibited xylose transport and showed noncompetitive inhibition of arabinose transport, likely because of inactivation of arabinose permease (Thurston et al., 1994). 

What Fraction of Extracellular Enzyme Activity Is Not Measured Using Current Methods  

As discussed in Section V, the spectrum of substrates and substrate proxies currently used to measure enzyme activities in marine systems is limited and most likely does not adequately represent the macromolecules actually available to aquatic microbial communities. Despite progress in recent years, our knowledge of the molecular structure and composition of dissolved organic matter is still only rudimentary. Although carbohydrates constitute an estimated 25-50% of DOC in seawater (Benner et al., 1992), 

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Fig. 6. Managing technology some key questions. Performance needs are examined for each of the five functions of technology management, at three...

Some Key Questions and Decisions Related to Inherently Safer Plant Design (Rogers et al., 1995)... 

Climate Change Science An Analysis of Some Key Questions, National Research Council, National Academy Press, Washington, D.C., 2001. 

Gas-phase results provide insight into the reaction pathways for isolated HE molecules however, the absence of the condensed-phase environment is believed to affect reaction pathways strongly. Some key questions related to condensed-phase decomposition are as follows (1) How do the temperature and pressure affect the reaction pathways (2) Are there temperature or pressure-induced phase-transitions that play a role in the reaction pathways that may occur (3) What happens to the reaction profiles in a shock-induced detonation These questions can be answered with condensed-phase simulations, but such simulations would require large-scale reactive chemical systems consisting of thousands of atoms. Here we present results of condensed-phase atomistic simulations, which are pushing the envelope toward reaching the required simulation goal. 

Among the wealth of issues relevant to hydrogen bonding in alcohol clusters, this review will focus on aspects related to hydrogen bond patterns and on the dynamical implications over a wide range of time scales. Some key questions connected to these aspects will be formulated. 

During this process some key questions are (1) Does the DNA sequence inserted into the expression vector contain all the sequences essential for the target protein (2) Is the messenger RNA expressed at the predicted length and produced in high enough levels (3) Does the recombinant protein react with antibody (4) Is there evidence of functional activity of the recombinant protein Methods for answering these questions are listed in Table 4.4. 

Some key questions that the water treatment sales/service engineer will need to resolve in order to produce a suitable biocide program include ... 

The computational study of the model system at QM level, followed by the ONIOM study on the real system, was able to answer some key questions about the asymmetric hydrogenation of alkenes. These theoretical investigations helped us to understand the anti-lock-and-key motif and the origin of the intriguing enantioselectivity upon changing the substituent of the al-kene from nitrile to f-Bu. 

Some key questions to be addressed as part of formulation, processing, and scale-up efforts include these ... 

Here then is our basic material, culled from a number of versions of the Daedalus/Icarus myth. There is more material than we could possibly use for a short screenplay, but we won t know which details will be important until we have answered some key questions. These are questions you may find it helpful to ask yourself each time you begin writing (or, for that matter, critiquing) a short screenplay. 

After the students have finished, help them sharpen their observation skills by asking them to respond to some key questions, such as these ... 

In recent years, a wealth of information on photolyase-mediated DNA repair and cryptochrome- and phototropin-mediated blue-light responses was obtained through the combined efforts of biologists, chemists, and physicists, from both experimental and theoretical studies. Here we have chosen recent examples of experimental work from our group to demonstrate the potential of modem EPR methods to answer mechanism-related questions and to study reactive intermediates in photo-induced electron transfer. Nevertheless, some key questions of these reactions remain to be solved. Important questions are as follows. What are the precise differences between CPD photolyase and (6 ) photolyase regarding... 

GAS EVOLUTION FROM THE DESIRED REACTION Many chemical reactions, whether exothermic, endothermic or thermoneutral, evolve non-condensable gases. In this case some key questions need to be answered in order to avoid hazardous situations ... 

The easiest way to identify whether there are any ergonomic issues at a school is to look at past injury data. OSHA 300 record keeping logs, past accident investigation reports, or insurance losses can help you determine whether any issues exist. Looking at this data and asking some key questions will help you identify and locate specific job tasks or occupations that have incurred ergonomic injuries. These questions should include ... 

When preparing for safety meetings, ask some key questions ... 

Here are some key questions you can answer in assessing the general orientation process in your facility ... 

Some key questions stUl remain. Is it better to improve more projects to less stringent but adequate standards than to build fewer projects to currently accepted standards for new highway construction Is it better to construct only those safety features that are cost-effective rather than bringing every feature of every project up to the latest standards The conundrum facing highway officials is how to decide which well-serving objectives can be met most cost-effectively. 

The following are some key questions that need to be considered before undertaking EM work. They are especially important if EM has never been done before, but even if it has, these questions are worth reconsidering as a reminder of what is involved in obtaining EM data. 

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